Imp.DiGregorio&Piras MAP OF THE LANDSCAPE UNITS AND GEOMORPHOSITES OF MONTE ARCI (SARDINIA) Felice Di Gregorio & Giuseppe Piras Department of Geology, Via Trentino 51, 09127 Cagliari - E-mail: geoam@unica.it ABSTRACT: F. Di Gregorio & G. Piras, Map of the landscape units and geomorphosites of Monte Arci (Sardinia). (IT ISSN 0394-3356, 2005). In the present paper a geomorphosites map is presented in which these sites are inserted in Landscape Units. The study area is the volcanic complex of Monte Arci in Central-West Sardinia. By means of a detailed geomorphological mapping, performed with the aid of photo-interpretation and direct surveys in the field, dif- ferent types of landscapes have been identified, according to their specific lithological, morphological and evolutive characteristics, that also have determined different types of landuse. It has been possible to distinguish the Landscape System of the Pliocene volcanites of Monte Arci that has been further subdivided in the following Landscape Units: - Landscape Unit of the acid lava’s; - Landscape Unit of the intermediate lava’s; - Landscape Unit of the alkaline trachites; - Landscape Unit of the basic lava’s. The eastern flank is substantially very different and is characterised by the Landscape System of the marine Miocene sedimentary deposits and the intra-Miocene volcanites, with recurrent rounded hills in marly-sandy terrains with discontinuous and sporadic out- cropping of infrasedimentary volcanic products mostly in relief. The Western flank instead is characterised by the Landscape System of the continental plio-quaternary sedimentary deposits, with flat and downhill landforms such as glacis and alluvial mostly inactive cones. Inside each of these Landscape Units several géomorphosites have been identified, mapped and classified according to their genesis, all with own specific scientific, didactic and cultural-tourist interests. This type of analysis and cartographic representation allows to comprise inside these fundamental reference units (Landscape Units and Systems) single punctual geomorphologic elements, showing their genesis in a better way, their spatial distribution and density and the possible relation with their surrounding environment. This kind of Map constitutes a valid basic information that allows to eva- luate the potential experience of the landscape as a fundamental instrument of knowledge in the territorial and landscape planning and in Environmental Impact Assessment Studies. RIASSUNTO: F. Di Gregorio & G. Piras, Carta delle unità di paesaggio e dei geomorfositi del Monte Arci (Sardegna). (IT ISSN 0394- 3356, 2005). Nel presente lavoro viene presentato un esempio di cartografia dei geomorfositi inseriti all’interno delle Unità di paesaggio che li con- tengono. L’area presa in considerazione è quella del complesso vulcanico del Monte Arci nella Sardegna centro-occidentale. Tramite un dettagliato rilevamento geomorfologico, condotto con l’uso della fotointerpretazione e di rilevamenti diretti in campo, nel- l’area sono state identificate alcune tipologie di paesaggio in base agli specifici caratteri distintivi geolitologici, morfologici ed evolutivi, ai quali corrispondono anche ben definite tipologie di utilizzazione del suolo. In sostanza, è possibile distinguere nel Monte Arci il Sistema di paesaggi delle vulcaniti plioceniche che, a sua volta, può essere classi- ficato nelle seguenti Unità: - Unità di paesaggio delle lave acide; - Unità di paesaggio delle lave intermedie; - Unità di paesaggio delle trachiti alcaline; - Unità di paesaggio delle lave basiche. Da questo si differenzia sostanzialmente il settore orientale, caratterizzato dal Sistema di paesaggi dei depositi sedimentari marini mio- cenici e delle vulcaniti intramioceniche, contraddistinto dalla ricorrenza di morbide forme collinari concave alla base e convesse verso l'alto, in terreni marnoso-arenacei con affioramento discontinuo e sporadico, generalmente in emergenza, dei prodotti lavici infrasedi- mentari. Il settore occidentale è, invece, caratterizzato dal Sistema di paesaggi dei depositi sedimentari continentali plio-quaternari, con forme pianeggianti e pedemontane, quali glacis e conoidi alluvionali, per lo più inattive. All’interno di ciascuna Unità di paesaggio sono stati identificati e cartografati i geomorfositi presenti distinti in base al processo geneti- co e al livello di interesse scientifico, didattico e turistico-culturale. Questo tipo di analisi e di rappresentazione consente di ricomprendere all’interno delle unità fondamentali di riferimento (Unità di pae- saggio e Sistemi di paesaggi) i singoli elementi geomorfici puntuali, lineari o areali, di esplicitarne meglio la genesi, la distribuzione e la densità nello spazio geografico. Questo metodo di analisi e rappresentazione costituisce una valida base conoscitiva per valutare il potenziale di esperienza del paesaggio, nella pianificazione territoriale e paesaggistica e negli studi di Valutazione di Impatto Ambientale (VIA). Keywords: Geomorphosites, Landscape Units, Landscape Systems, Central-West Sardinia, Monte Arci, Valorisation. Parole chiave: Geomorfositi, Unità di paesaggio, Sistema di paesaggi, Sardegna centro-occidentale, Monte Arci, Valorizzazione. Il Quaternario Italian Journal of Quaternary Sciences 18(1), 2005 - Volume Speciale, 267-273 268 F. Di Gregorio & G. Piras 1. INTRODUCTION In the present paper a géomorphosites map is presented in which these sites are inserted in Landscape Units. The study area is the volcanic com- plex of Monte Arci in Central-West Sardinia. The Landscape Unit represents a fundamental taxonomic unit in a methodological approach of map- ping of the resources of a territory based especially on its physical characteristics (Clemente, 1987; Di Gregorio, 1987; Piacente et al., 2000; Poli et al, 1994; Romani, 1994; Turri, 1979); this allows to describe with greater detail the areas with a recurrent lithological, morphological and pedological pattern that are geneti- cally related, or else geographical units with specific, distinctive and homogeneous characteristics of forma- tion and evolution (Tricart & Kilian, 1979; Piacente, 1999; Romani, 1994; Sestini, 1963). This approach also permits to individuate significant elements of the land- scape (Panizza, 1988), as has clearly been demonstra- ted by earlier experiences such as the Territorial Landscape Plan of the Emilia-Romagna Region (1987). The Landscape Units are generally considered singularly or in association with other units forming Systems with peculiar genetic or evolutive connections; in other cases the Landscape Units are subdivided in single components depending on the complexity of the study area and of the desired cartographic detail (FAO, 1983). The recognition of Landscape Units and Systems is possible by means of methods for the territorial analysis of vast regions, essentially based on remote sensing techniques or on aerial photo-interpretation. The principal fundament of validity of this type of approach relies on the fact that the landscape configu- ration, using geomorphologic analysing method, is the easiest characteristic of the physical attributes of a ter- ritory to recognise, classify and represent. In particular, according to the lithologic-morpho- logic criteria it is possible to individuate different funda- mental Landscape Units all of which give birth to spatial entities characterised by a distinct set forms and diffe- rent from others on the base of the single constituting components. In this manner a classification of the geo- graphic space is configured, principally based on the analysis of the geological constitution and the charac- terising landforms, considering that these are the expression of the evolution and of a dynamical earth surface that is realised by the interference of natural and human processes and phenomena. Regrouping the Landscape Units with homoge- neous genetic and evolution characteristics it is possi- ble to define Landscape Systems. Thanks to the recognition and the classification of these distinct litho-morphological units it is thus pos- sible to make an easier reading of the territory and a more immediate and accurate qualification of the natu- ral resources, in particular of those that constitute the peculiar physical traits because collocated in the same spatial context; in contemporary it is possible to indivi- duate the situations of interference between natural and human factors, or a combination of these, for a more rational use and tutelage of the same resources and a better insertion in eventual settlements and infrastructu- res in the natural and human existing landscape (Clemente, 1987). This methodology has been applied in the Monte Arci area, in central-west Sardinia, collimating particu- larly the attention on the relationship between geosites and géomorphosites, Landscape Units and Systems (Tab. 1). 2. GEOLOGICAL AND GEOMORPHOLOGICAL ASPECTS OF MONTE ARCI Monte Arci is an important Tertiary and Plio- Quaternary volcanic complex characterised by a wide variety of effusive rocks and interesting structural or residual landforms derived from ancient palaeogeo- graphic and palaeoclimatic events. The products of the volcanic activity that can be found on Monte Arci are referable to two different chro- nological events, each of which have distinct precise volcanologic and geodynamic characters. To the intra-Miocene volcanism, referable to the tectonic evolution of the Western Mediterranean (Cherchi & Montadert, 1982) are correlated mostly discontinuous outcrops intercalated in the marly-arena- ceous Miocene sediments of Marmilla (Maccioni, 1969; 1974), constituted of basic rocks with calco-alcaline affinities, related to a submarine volcanism dated 19÷5 My (Savelli, 1975; Di Paola et al., 1975). Such outcrops are constituted, from bottom to top, by submarine pil- low lava’s with infrasedimentary hyaloclasts and mono- genetic breccia of pillow lava’s with minor presence of hyaloclasts. To the Late-Pliocene cycle the emission of the lava’s that have originated the volcanic complex of Monte Arci during distensional phenomena of the conti- nental Sardinian plate and the formation of the tectonic graben of Campidano are attributed, with basic, inter- mediate and acid rocks related to subaerial volcanism. Radiometric dating (Belluomini et al., 1970; Belluomini & Taddeucci, 1970; Savelli, 1975; Di Paola et al., 1975; Bigazzi et al., 1976; Beccaluva et al., 1985; Montanini, 1992; Montanini & Villa, 1990, 1993) has allowed to date the Pliocene volcanic activity between 5 and 2.6 My. The succession of volcanic products recognised by several Authors (Di Paola et al., 1975; Beccaluva et al., 1975, 1977; Assorgia et al., 1975; 1976), from bot- tom to top is represented by: - Acid lava’s, constituted of rhyolite-rhyodacite flows with transition of lithoid facies to perlite-obsidian facies with associated pyroclastic levels; - Intermediate lava’s, mainly dacitic and subordinately andesitic, with evident slabby fissuring; - Alcaline trachites, sometimes passing to vitrophyric facies; - Basic lava’s, separated in basaltic andesites, basalts with an alkaline chemistry and subalcaline basalts; The Plio-Quaternary continental sedimentary deposits are mainly composed of: - Conglomerates, sands and more or less compact clays, mainly composing alluvial cones and glacis (ancient alluvium Auct.); - Recent and present alluvium along river beds. Altogether Monte Arci has a typical form of ellip- tic ridge elongated in N-S direction that reaches its highest altitude at the neck named Trebina Longa (812 m a.s.l.). The Western sector that overviews the Campidano is composed of volcanic flows, mostly rhyolite, deeply cut by valleys that flow into the plain. The Eastern sector is characterised by a morphology of plateau with different almost horizontal plains limited by rocky cliffs and steep surfaces that form a clear contra- st with the sweet hills of the Marmilla. 269Map of the landscape units ... 3. THE LANDSCAPE SYSTEMS AND UNITS OF MONTE ARCI To facilitate the individuation of the géomorpho- sites, according to the definition given by Barca & Di Gregorio (1991) and by Panizza & Piacente (1989), on Monte Arci firstly the territory has been subdivided in Landscape Units and Systems (Fig. 1). In more detail, using lithological and morphological criteria the main Tab. 1 - Systems and Landscape Units of Monte Arci. Sistemi e Unità di Paesaggio del Monte Arci. Landscape System Landscape Unit Location General Morphology Summary of main physical features 1 Plio-Quaternary Recent and modern Riu Florissa, More or less V- or - enclosed valleys sedimentary-continental alluvium of main river Riu Tumboi, U-shaped enclosed - waterfalls deposits beds Gora Tappoi valleys Glacis and alluvial Pranu Tiria, Pranu Forru, Largely inactive glacis - glacis fans Madala, Mandronis, and alluvial fans - alluvial fans Sa Giara, Pira Inferta S’Argioledda 2 Pliocene volcanic Basic lava flows Pranu Terra, Pranu Near horizontal or - basalt plateaus rocks Mallu,Pranu Santa Lucia, gently undulating - temporary wetlands Su Tasureddu, Campu basic lava plateaus - dykes Serrau, Apruna, Acqua and lava flows - necks Marzana, Arrideli, - lava domes Benazzeddus, Corona - column jointing Su Pardu, Pranu Murta, Pranu Pira, Pranu Sibiriu Trachytic lava flows Punta Quebiois, Is Benas Rugged, porphyry - small cavities and Serra Arruidroxiu, Punta and intensely tafoni S’Orziada, Punta Masoni honeycomb-weathered - slightly enclosed Perdu, Rocce Su rock outcrops valleys Colombariu - near vertical walls Intermediate lava Costa Pisu, Braxelogu, Gently inclined lava - lava flows flows (andesite and Pranu Piccinu, flows often fractured - fractures with slab dacite) Cuccuru Mattivi, Conca and slab-like, like geometry Mraxi, Bruncu su Copiu surrounded by near - near vertical rock vertical rock walls walls - enclosed valleys - pseudo-karst cavities - waterfalls Acid lava flows Punta Laccu Sa Vitella, Rugged landforms - enclosed valleys (rhyolitic, rhyolitic- Genna Spina, Perdas with steeply inclined - pyroclastic rhyodacitic) often in Urias, Punta Nicola slopes, sharp breaks sequences perlite-obsidian Pani, Conca S’Ollastu, of slope and - obsidian deposits facies, sometimes Punta Su Cantareddu, enclosed valleys - tafoni associated with Mt. Sparau - perlite quarries pyroclastic strata 3 Miocene sedimentary Marly-sandy Cea Pedrixi, Repetitive, gently - repetitive rolling marine deposits and sediments Sa Spendula, rolling hills on hills intra-Miocene intercalated with Truncheddu, Cannisone, marly-sandy terrains - enclosed valleys volcanic rocks submarine basic Pranu Espis, Serra with discontinuous - pillow lavas pillow or brecciated Craboni, Pala Sa Murta, and sporadic outcrops - waterfalls lavas, with Su Entosu, Santa Maria, of intrasedimentary associated Corona Fraus lava products hyaloclastites 270 F. Di Gregorio & G. Piras 1 2 3 1 1 1 2 2 2 2 2 2 2 3 3 3 VILLA VERDE PAU ALES Pitzu Tenuru ZEPPARA P ra nu E sp is P.ta Pizzighinu Apruna Corongiu Sitzoua Rocca Tressa Is M u ru s Trebina Longa Conca Mraxi Trebina Lada P.ta Trunconi P a ri s d e B e n a s Is B e n a s P.ta Perda de Pani Cuccuru Mattivi Pranu Pira CURCURIS POMPU MASULLAS MORGONGIORI P ra n u I s F o g a ia s Conca Cannas Rocce su Colombariu P ra n u S ib ir iu SIRIS C o ro n a F ra u s S u P ia li URAS VILLAURBANA P ra nu M al lu P ra M a rr a d a C o sta P isu P ranu Terra Monte 'e Cres ia TIRIA Pranu Tiria C a m p u T o m a su Pranu Santa Lucia Campu Forru Pira Infe rta Mason gius B r a x e l o g u P.ta Corongiu Mela P.ta Pranu Staddas Genna Spina Genna Cruxi Perdas Urias SANT'ANNA ESCOVEDU USELLUS P ra n u M u rt a 2 1 1 1 2 P.ta su Zippiri Conca s'Ollastu Cuc.ru Aspru Landscape System of the Pliocene volcanites Acid lava's, constituted of rhyolite-rhyodacite flows with transition of lithoid facies to perlite-obsidian facies with associated pyroclastic levels Intermediate lava's, mainly dacitic and subordinately andesitic, with evident slabby fissuring Alcaline trachites, sometimes passing to vitrophyric facies Basic lava's, separated in basaltic andesites, basalts with an alkaline chemistry and subalcaline basalts Landscape System of the continental Plio- Quaternary sedimentary deposits Conglomerates, sands and more or less compact clays (ancient alluvium Auct.) Debris Recent and present alluvium along river beds, alluvial cones and glacis Landscape System of the marine Miocene sedimentary deposits and the intra-Miocene volcanites Marly-arenaceous Miocene sediments of Marmilla; submarine pillow lava's with infrasedimentary hyaloclasts and monogenetic breccia of pillow lava's with minor presence of hyaloclasts. Limit of Landscape System Faults and fractures Town Geomorphosites Conventional signs LEGEND 1 2 3 Fig. 1 – Map of the Landscape Units and Systems of Monte Arci Carta dei Sistemi e Unità di paesaggio del Monte Arci. 271 geomorphological units have been identified, all of which give rise to a landscape with precise, distinctive and homogeneous genetic and evolutive characters. Following these criteria the Landscape Systems have been recognised and, for each of these, have been distinguished the Landscape Units and also the single physiographic components present in them. Practically, from the performed research using detailed field work and photo-interpretation, it has been possible to distin- guish the Landscape System of the Pliocene volcanites of Monte Arci that has been further subdivided in the following Landscape Units: - Landscape Unit of the acid lava’s, characterised by an articulated and uneven morphology especially where massive rhyolites crop out, with steep sides and clear breaks of slope where the less resistant perlite-obi- sian facies are surfacing and the presence of a well developed fluvial network, typical of the Western flank; - Landscape Unit of the intermediate lava’s, characteri- sed by a plateau morphology on the lava flows reco- gnisable by the slabby fissuration of the rocks; - Landscape Unit of the alkaline trachites with landforms prevalently related to meteoric subaerial processes with hollows and tafoni; - Landscape Unit of the basic lava’s characterised by table-like morphologies bordered by vertical cliffs or steep slopes. From these units the Eastern flank is very diffe- rent, characterised by the Landscape System of the marine Miocene sedimentary deposits and the intra- Miocene volcanites, characterised by recurrent rounded hills in marly-sandy terrains with discontinuous and sporadic outcropping of infrasedimentary volcanic pro- ducts mostly in relief. The Western flank instead is characterised by the Landscape System of the continental plio-quaternary sedimentary deposits, with flat and downhill landforms such as glacis and alluvial mostly inactive cones. 4. THE GEOMORPHOSITES Inside the Landscape Units of Monte Arci many géomorphosites have been identified (Tab. 2) that represent a high didactic and scientific value, as testi- monies of particular past and still ongoing evolutive geological and geomorphological processes (Barca et al., 1997; Di Gregorio & Piras, 1997). Some of these géomorphosites can be considered as single or isola- ted elements (Sa Perda Sperrada, the columnar fissu- ring of Is Aruttas Santas, the andesitic Megapillow of Gutturu Forru and the isolated outcrops of pillow lava’s, the volcanic necks of Trebina Longa and Trebina Lada, the waterfalls of Sa Spendula and Su Fustiolau) others are better identified as linear morphotypes (the cliffs of Conca Mraxi and the pyroclastic levels at their foot, the river Riu Tumboi and its tributaries, the emerging basal- tic dykes of Is Murus, Corongiu Sitzoua, Acquafrida, Paris de Benas, Sa Dispensa) or as aerial more or less relevant sites (the basaltic plateau of Pranu Santa Lucia and the temporary wetlands called paulis on its summit, the tafoni of Is Benas, Rocce su Colombariu and Conca s’Ollastu, the steppe-like environments of Campu Forru and Pranu Tiria). Some of these sites (the hypogean Neolithic burial of Su Segretu de sa Conch’e s’Omini, the nuragic hypo- gean temple of Sa Grutta de is Coambus, the obsidian sites of Perdas Urias, Conca Cannas and Tzipaneas) have a great archaeological interest, as testimonials of the life and the artefacts of the ancient populations that have lived in this territory, founding the seam of the Nuragic culture started with the industry of the obsidian that took up the confront with many other Mediterranean cultures. 5. CONCLUSIONS Geomorphosites are among the multiple and complex environmental components of the landscape that need to be studied and on which whatever Territorial and Environmental Planning should be based, occupying a fundamental role for their value as a non renewable resource, sometimes unique for their intrin- sic characteristics. Possible risks for the integrity or the complete destruction of this heritage can be avoided only by a detailed territorial analysis founded on the impact assessment of the projects regarding the occupation of the soil, the use of the natural resources and the urba- nisation. By means of a detailed geomorphological map- ping, performed with the aid of photo-interpretation and direct surveys in the field, different types of landscapes have been identified at Monte Arci (Central-West Sardinia), according to their specific lithological, morphological and evolutive characteristics, that also have determined different types of landuse. Inside each of these Landscape Units several géomorphosites have been identified, mapped and classified according to their genesis, all with own specific scientific, didactic and cultural-tourist interests. This type of analysis and cartographic represen- tation allows to comprise inside these fundamental reference units (Landscape Units and Systems) single punctual geomorphologic elements, showing their genesis in a better way, their spatial distribution and density and the possible relation with their surroun- ding environment. This kind of Map constitutes a valid basic information that allows to evaluate the potential experience of the landscape as an fundamental instru- ment of knowledge in the territorial and landscape planning and in Environmental Impact Assessment Studies. The cartographic work of recognition of the Landscape Units and Systems has allowed to identify various géomorphosites. The adopted analysis and the evaluation of these géomorphosites inside a physio- graphic reference unit permits to reveal a predominan- ce of sites in the Landscape Units of the Tertiary volca- nic rocks, showing a more relevant geodiversity and a higher Multiple Value (Di Fidio, 1990) of landscape ele- ments that can be used for e recreational experience of the landscape by Geotourism. Map of the landscape units ... 272 F. Di Gregorio & G. Piras Tab. 2 – Geomorphosites of Monte Arci. I Geomorfositi del Monte Arci. Landscape System of the Pliocene volcanic rocks Name Municipality Location I.G.M. reference Genetic Rock type Genetic Classification definition Basalt flows landscape Unit 1 - Trebina Longa - Morgongiori Porteddu Murus 539 IV MK78300288 Volcanic Basalt Volcanic necks Trebina Lada 2 - Pranu Santa Lucia Villav. - Usellus Pranu Santa Lucia 529 III MK82450798 Volc.-Struct. Basalt Volcanic plateau 3 - Paulis del Pranu Santa Lucia Villav.- Usellus Pranu Santa Lucia 529 III MK83050950 Lacustrine Basalt Temporary basins 4 - Sa Perda Sperrada Masullas Perda Sperrada 539 IV MJ79039546 Struct.-Meteoric Basalt Morphosculpture 5 - “Is Murus” dyke Marrubiu Is Murus 539 IV MK76930385 Volcanic Basalt Outcropping dyke 6 - “Corongiu Sitzoua” Marrubiu Corongiu Sitzoua 539 IV MK76930495 Volcanic Basalt Outcropping dyke dyke 7 - “Acquafrida” dyke Ales Acquafrida 529 III MK78200593 Volcanic Basalt Outcropping dyke 8 - “Paris de Benas” Morgongiori Paris de Benas 539 IV MK78340113 Volcanic Basalt Outcropping dyke dyke 9 - “Sa Dispensa” dyke Palmas Arborea Sa Dispensa 529 III MK77810878 Volcanic Basalt Outcropping dyke 10 - Is Aruttas Santas Villaurbana Is Aruttas Santas 529 III MK78631228 Volc. – Struct. And.– basalt. Columnar jointed basalt columns basalt Intermediate lava flows landscape Unit 11 - “Cliffs” at Conca Ales - Pau - Conca Mraxi 539 IV MK80750245 Struct. - Slope Rhyolite - Sheer volcanic Mraxi Morgongiori Dacite walls 12 - “Sa Spendula” Ales Cadresa 539 IV MK80250338 Fluvial – Struct. Dacite Waterfall waterfall 13 - Riu Tumboi and Villaurbana Riu Tumboi 529 III MK80051245 Fluvial – Struct. Dacite – And. Small fluvial valleys affluents 14 - Sa Grutta de is Morgongiori Punta Santu Marcu 539 IV MK79950093 Anthropogenic Dacite Natural cavities Coambus hypogeum temple ipogeo 15 - Su Segretu de sa Villaurbana Braxelogu 529III MK80101043 Anthropogenic Dacite Natural cavities Conch’e s’Omini hypogeum Alkali trachitic lava flows landscape Unit 16 - Is Benas Morgongiori Is Benas 539 IV MK79250150 Meteoric Trachyte Honeycombed rock 17 - Rocce su Masullas Rocce su 539 IV MJ77989695 Meteoric Trachyte Honeycombed rock Colombariu Colombariu Acid lava flows landscape Unit 18 - Conca s’Ollastu Marrubiu - Conca s’Ollastu 539 IV MK73550217 Meteoric Rhyolite Honeycombed rock Morgongiori 19 - Layers of Ales - Conca Mraxi 539 IV MK80750245 Volcanic Pyroclastic Pyroclastic pyroclastic rock Morgongiori rock sequences 20 - Conca Cannas Masullas Conca Cannas 539 IV MJ77389713 Volcanic Rhyolite Obsidian deposit obsidian deposit 21 - Perdas Urias Pau Perdas Urias - 529 III MJ80360621 Volcanic Rhyolite Obsidian deposit obsidian deposit Sennixeddu 22 - Tzipaneas Marrubiu Tzipaneas 539 IV MK76530371 Volcanic Rhyolite Obsidian deposit obsidian deposit Landscape System of the Miocene marine sedimentary deposits and IntraMiocene volcanic rocks 23 - “Fustiolau” Pau Truncheddu 539 IV MK80930684 Fluvial – Struct. Marl – Aren. Waterfall waterfall 24 - Megapillow at Masullas Gutturu Forru 539 III MJ83509418 Volcanic Andesite Andesitic Gutturu Forru megapillow 25 – Outcrops of Masullas - Siris Santa Maria - 539 IV MJ79089557 Volcanic Basalt – And. Pillow lava pillow lava - Morgongiori Pala Sa Murta Landscape System of the Plio-Quaternary continental sedimentary deposits 26 – Steppe Palmas Arborea - Campu Forru - 529 III MK76111039 Fluv. – Anthrop. Alluvia Steppe environments at Oristano Pranu Tiria environments and Campu Forru and lakes in hills Pranu Tiria REFERENCES ASSORGIA A., BECCALUVA L., DI PAOLA G.M., MACCIONI L., MACCIOTTA G., PUXEDDU M., SANTACROCE R. & VEN- TURELLI G. (1975) - Carta geopetrografica del com- plesso vulcanico del monte Arci (Sardegna) 1:50.000 - Grafiche STEP, Parma. ASSORGIA A., BECCALUVA L., DI PAOLA G.M., MACCIONI L., MACCIOTTA G., PUXEDDU M., SANTACROCE R. & VEN- TURELLI G. 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