untitled Holocene development of the Pennala basin with special reference to the palaeoenvironment of Meso- and Neolithic dwelling sites, Lahti–Orimattila, Southern Finland TOMMI SIRVIÖ AND MERI KAJANDER Sirviö, Tommi and Meri Kajander (2003). Holocene development of the Pen- nala basin with special reference to the palaeoenvironment of Meso- and Ne- olithic dwelling sites, Lahti–Orimattila, Southern Finland. Fennia 181:1, pp. 85–101. Helsinki. ISSN 0015-0010. The Holocene development of the Pennala basin, Southern Finland, was stud- ied using lithostratigraphical and biostratigraphical methods, shore level sur- veys and radiocarbon dating in the areas adjacent to the I Salpausselkä ice- marginal formation. The study results give an improved picture of the shore- line displacement and palaeoenvironment of the Pennala basin during the pe- riod of 10000–2500 14C yr BP (ca. 11400–2600 cal yr BP). The results indicate that the Ancylus Lake stage in the Pennala basin oc- curred during the Preboreal and Early Boreal chronozones around 9600–8900 14C yr BP (ca. 10900–10 000 cal yr BP). The transgression was followed by a long-term lake phase, which ended, due to overgrowth of the basin, at ca. 2900 14C yr BP (ca. 3000 cal yr BP). The highest Ancylus shoreline in the area is lo- cated at 71 m a.s.l. The altitude of the ancient Pennala Lake is located at 68.5 m a.s.l. The Pennala basin and adjacent areas were inhabited by Stone Age dwellers during the Middle Neolithic period. The dated evidence of the Early Mesolithic settlement in the area remains scarce. During the Early Mesolithic period the Pennala basin was a sheltered bay of the Ancylus Lake and during the Middle Neolithic period of settlement ca. 5500–3500 14C yr BP (ca. 6300–3800 cal yr BP) the basin served Neolithic dwellers as a small inland lake. Tommi Sirviö, Department of Geography, P.O. Box 64, FIN-00014, University of Helsinki, Finland; Meri Kajander, Department of Geology, Division of Ge- ology and Palaeontology, P.O. Box 64, FIN-00014, University of Helsinki, Fin- land. E-mail: tommi.sirvio@helsinki.fi, meri.kajander@helsinki.fi. MS received 12 September 2002. Introduction Shoreline displacement during the Ancylus Lake stage in Southern Finland ca. 9500– 8000 14C yr BP The first evidence of a transgression that had oc- curred at the beginning of the Ancylus Lake stage was discovered in Southern Finland and Karelian Isthmus (Hyyppä 1937, 1943). Since then the na- ture, extent and dating of the Ancylus transgres- sion in Southern Finland have been discussed and modified by several authors (e.g., Tynni 1966; Ero- nen 1976; Eronen & Haila 1982; Glückert & Ris- taniemi 1982; Ristaniemi & Glückert 1987; Ma- tiskainen 1989b; Glückert 1991). The Ancylus transgression in Southern Finland began 9700–9500 14C yr BP (ca. 11200–10 700 cal yr BP) and reached its maximum level at 9200–9000 14C yr BP (ca. 10300–10200 cal yr BP) (Eronen & Haila 1982; Glückert & Ristaniemi 1982; Ristaniemi & Glückert 1987; Glückert 1991). The Ancylus transgression was followed by a rapid regressive stage of the lake, which in Southern Finland occurred around 9000–8000 14C yr BP (ca. 10200–8900 cal yr BP) (e.g., Eronen & Haila 1982). The altitude of the Ancylus shore lev- el (the Ancylus limit) at the time of transgression 86 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander maximum has been placed at 64–74 m a.s.l be- tween the Helsinki–Pukkila and the II Salpaus- selkä isobases of current land uplift (Tynni 1966; Eronen & Haila 1982; Glückert & Ristaniemi 1982). The Ancylus limit is located approximate- ly at 70 m a.s.l. in Lohja (the I Salpausselkä), and the amplitude of the transgression in the same area was 4–5 metres (Ristaniemi & Glückert 1987). The regressive stage of the Ancylus Lake led to the final isolation of several independent basins. Some of these basins have remained as lakes to the present day while others have dried-up dur- ing the post-glacial time due to peat overgrowth and sedimentation. Finally, in order to increase the area of agricultural land, many lakes in South- ern Finland were destroyed between 18th and 20th centuries by lowering the water level of the lakes or by totally drying them up. Layers of gyttja typically indicate the lake stag- es in the sediments and these layers have been reported from several locations under peat depos- its. Overgrowth of these presently non-existing lakes have been, in many cases, reported as “side products” from studies that seek isolation contacts and indicators of transgressions under peat bogs (e.g., Jantunen 1995). Korhola (1990a) has rough- ly estimated that in the Southern zone of raised bogs, at least 20% of the bogs were formed by overgrowth. The development history of such overgrown lakes has been of minor interest of ge- ologists, geographers and archaeologists with few exceptions (e.g., Korhola 1990b; Tikkanen & Kor- hola 1993). The currently studied Pennala basin is one example of an overgrown lake isolated dur- ing the Ancylus regression. This paper will make a special reference to archaeological data and show the importance of such ancient lakes to Stone Age dwellers. Palaeoenvironments and dating of Stone Age dwelling sites The dating of Mesolithic and Neolithic (Stone age) dwelling sites in Finland has been traditionally based on known shore displacement of the Baltic Sea, the altitudes of dwelling sites and type of ar- tefact found at excavation sites (e.g., Siiriäinen 1973; Matiskainen 1989a; Hyvärinen 1999). With a few exceptions, most of the Mesolithic and Ne- olithic dwelling sites are assumed to have been located very close to the shorelines and the ar- chaeological shoreline displacement chronologies have been based on assumption that the prehis- toric site must have been located in close con- tact with the shoreline of its time (Siiriäinen 1982; Matiskainen 1989a). The chronology of the Mesolithic presented by Matiskainen (1989a) is divided into two chrono- logical stages: Ancylus Mesolithic 9300–8000 14C yr BP (ca. 10450–8900 cal yr BP) and Litorina Mesolithic 8000–6000 14C yr BP (ca. 8900–6800 cal yr BP) stages. The Mesolithic stage was fol- lowed by the Neolithic period, during which Comb Ware ceramics was common in Finland. The upper limit of the Neolithic period has been defined at ca. 2500 14C yr BP (2600 cal yr BP) (Siiriäinen 1982). During the Holocene (and Mesolithic) the pal- aeoenvironment in Finland was unsteady, and the Stone Age dwelling sites were subject to large scale environmental changes such as deglacia- tion, land uplift, shore displacement of the Baltic and development of vegetation (Siiriäinen 1987; Matiskainen 1989b). The shore-level fluctuations and overgrowth of small lakes, however, have been widely bypassed by researchers, whereas possible overgrown lakes in Porvoonjoki River valley have been found in preliminary studies from several locations including Kanteleenjärvi (Pukkila) and Luhdanjoki (Lahti–Hollola) areas (Sirviö 2000; Sirviö et al. 2002). The most comprehensive studies made on pal- aeoenvironments of Stone Age dwelling sites in Finland have been presented by Matiskainen (1989b) who reconstructed the palaeoenviron- ment of the Mesolithic dwelling sites 10000–6000 14C yr BP (ca. 11400–6800 cal yr BP) based on shore displacement, vegetation history, refuse fau- na and archaeological artefacts found from Asko- la area 40 km south of the Pennala basin. It was concluded that emergence of new land during the rapid Ancylus regression forced Early Mesolithic settlements to move south from the Porvoonjoki River valley down to the Askola region in order to carry on a subsistence strategy in a similar ar- chipelagic palaeoenvironments. The postglacial vegetation history during the Mesolithic and Neolithic stages in Southern Fin- land is well known (e.g., Donner 1971). The re- search on the vegetation history close to the Pen- nala basin includes studies made on the Työtjärvi Lake, Varrassuo bog (Hollola) (Donner et al. 1978), Joutjärvi and Alasenjärvi Lakes (Lahti) (Vuorela 1978). According to the analysed pol- len on the Työtjärvi core, the first indication of FENNIA 181: 1 (2003) 87Holocene development of the Pennala basin with special … forest clearing in the area occurred ca. 5600 14C yr BP (ca. 6400 cal yr BP). Pollen analyses on Työtjärvi and Varrassuo cores have indicated that the slash-and-burn agriculture arrived in the area ca. 3200–2400 14C yr BP (ca. 3400–2400 cal yr BP) (Donner et al. 1978). Site description The Pennala basin The Pennala basin (Figs. 1 and 2) is located 5 km south of the I Salpausselkä, by the border of Lahti Fig. 1. The location of the study area in southern Finland. A) Location of the investigated Pennala basin south of Lahti, and isobases of current land uplift (mmyr–1). B) The extent of the Pennala drainage area and the extent of Ancylus Lake during the transgression maximum at ca. 9100 14C yr BP (ca. 10200 cal yr BP) with reference to the Mesolithic Ristola dwelling site. C) The extent of the ancient Pennala Lake at 8900–2900 14C yr BP (ca. 10000–3000 cal yr BP) and the maximum coverage of Ancylus Lake with reference to the location of Mesolithic and Neolithic dwelling sites and raised shore forma- tions. 88 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander and Orimattila communes (60°55'N, 25°42'E). The altitude of the basin varies from 66.6 m a.s.l. (the threshold) to 130 m a.s.l. (Renkomäki hill) and both heights are located in the northern parts of the drainage basin. The Rengonjoki River flows gently to the north in the middle of the basin. The middle parts of the Pennala basin consist of flat, low-lying and mostly cultivated areas at 67.5–70 m a.s.l. The width of flat and low-lying area varies between 200–600 m and is widest in the middle and northern parts of the basin. The length of the flat area is approximately 3.5 km. The low-lying area consists of 1.3–1.7 m thick lay- er of Carex and Sphagnum peat, below which a deposit of gyttja and clay gyttja over 3 m thick is present. Another noticeable peat deposit, the Pih- lajasuo bog (70.5 m a.s.l.), is located in the vil- lage of Pennala at the southern end of the drain- age basin. In general, the areas located slightly over 70 m a.s.l. consist of clayey and silty soils, and are in most cases cultivated. Higher altitudes, on the other hand, are dominated by forests and contain till and unevenly distributed sand and gravel deposits of glaciofluvial origin re-worked by wave action (for example the Renkomäki, Latomäki and Pyssymäki hills). The total area of the drainage basin is approximately 24 km2. Earlier archaeological studies in the Pennala basin A total of 12 Stone Age dwelling sites and one secondary site (float of bark) have been found in the Pennala basin (Poutiainen & Takala 2001). The altitudes of the dwelling sites vary between 68.5– 75.5 m a.s.l. Several other Stone Age dwelling sites have been found in the adjacent areas, in- cluding Ristola (e.g., Matiskainen 1989b; Takala 1999), Luhdanjoki (Lahti–Hollola), Puujoki (Ori- mattila) and Kanteleenjärvi (Pukkila) (e.g., Pou- tiainen 1998). The first archaeological finds in the Pennala basin were made in 1948 (Itkonen 1949). A wooden sledge-runner was found beneath peat deposits (depth 1.6 m) from the western side of the Rengonjoki River, near the Alestalo dwelling site. The find resulted in pollen analytical studies (Valovirta 1949), based on which the sledge-run- ner was dated to the stage, typical of Comb Ware ceramics ca. 5000 14C yr BP. Further small exca- vations were carried out in the same year on the eastern side of the Rengonjoki River at Maijanoja dwelling site at approximately 70 m a.s.l. (Luho 1950). A second period of excavations was carried out during 1959. The most important finds at the Al- estalo dwelling site contained pieces of Comb Ware ceramics (at 67.0–67.3 m a.s.l.) and rem- nants of a hearth (68.6–68.8 m a.s.l.) (Meinander 1960). Two radiocarbon dates, 5370 ± 140 and 4840 ± 190 14C yr BP (ca. 6200 and 5600 cal yr BP), were obtained from a layer of Comb Ware ceramic pottery, rich in Trapa natans (water chest- nut) fruits (Meinander 1971). Vuorela (1981) carried out pollen stratigraphi- cal studies of the Pennala basin in the immediate vicinity of the Alestalo and Uusitalo dwelling sites (Fig. 1). A radiocarbon date 5310 ± 110 14C yr BP (ca. 6100 cal yr BP) was obtained from the previ- ously mentioned level containing the sledge-run- ner and remnants of Trapa natans. Despite the presence of several Stone Age dwelling sites in the vicinity, apophytic evidence in the stratigraphy Fig. 2. The Pennala basin northwest of Pyssymäki Hill. The investigated coring site is marked with an arrow and the shore level of the ancient Pennala Lake with a broken line. (Photo: Tommi Sirviö). FENNIA 181: 1 (2003) 89Holocene development of the Pennala basin with special … were too scarce to indicate a clear influence of human activities on vegetation. A distinct change in the upper part of the stratigraphy (including a change from coarse gyttja to peat) was interpret- ed as indicating the final drying up of the basin (Vuorela 1981). Layers rich in Trapa natans mac- ro remnants were interpreted as cultural layers with fruits crushed by Stone Age dwellers (Aalto 1981). Vuorela (1981) concluded that water chest- nut was possibly favoured or even intentionally cultivated in the area. The most recent excavations in the Pennala ba- sin have been carried out on five dwelling sites (Myllyoja, Alestalo, Uusitalo, Metsämäki 1 and Metsämäki 2) during 2000–2002. The majority of the finds of the recent excavations were made from the Myllyoja dwelling site located in the northern end of Pennala basin at 69.0–71.5 m a.s.l. Most of these finds consisted of ceramics from the Neolithic substages, and possible hearth remnants were found at 69.5–69.6 m a.s.l. (Pou- tiainen 2001). The preliminary results of the radi- ocarbon dating showed that the oldest date ob- tained from a burnt bone belonged to the Early Mesolithic period ca. 9300 14C yr BP (ca.10500 cal yr BP). Two other radiocarbon dates were ob- tained from the Neolithic ceramics, ca. 4000 14C yr BP (ca. 4500 cal yr BP), and one from char- coal, ca. 1200 14C yr BP (ca. 1100 cal yr BP) (Pou- tiainen 2002). The excavations carried out at the Alestalo and Uusitalo dwelling sites consisted of findings that included quartz artefacts, ceramics, and burnt bone. Most of the finds were made be- tween 67.8 and 70.6 m a.s.l. (Takala 2001). The dwelling sites of Metsämäki 1 and 2 are located noticeably above the dominating, low-ly- ing level of the basin to the east of the Rengon- joki River at ca. 73–75.5 m a.s.l. (Poutiainen & Takala 2001). The finds made at the excavations in summer 2002 included quartz and ceramics, which suggest that the sites were inhabited at least during the Late Neolithic stage (Poutiainen 2002; Takala 2002). The Ristola dwelling site is located adjacent to the Porvoonjoki River, approximately 4 km northwest from the Pennala basin at 68–75 m a.s.l. The first finds from the Ristola site were made in 1966, and preliminary excavations were carried out during 1970–1971. More comprehen- sive excavations were carried out during 1995– 1999 (Takala 1999). The most important finds from the site included flint artefacts and flake frag- ments, comparable to the Kunda Culture and Pulli site in Southern Estonia, dating back to the Early Mesolithic period. The radiocarbon age ca. 9250 14C yr BP (ca. 10500 cal yr BP) of the Ristola site gains support also from shore displacement chro- nology (Ristaniemi & Glückert 1987; Matiskain- en 1989b). The radiocarbon dates from the in situ structures found at the site are much younger (from Neolithic to recent) than the typology of the artefacts and location of the site would suggest (Takala 1999; Takala 2002). Field and laboratory methods To verify the assumed levels of the Ancylus trans- gression and the ancient Pennala Lake, the alti- tudes of the raised shorelines and the threshold (Figs. 3 & 4) were surveyed in the area close to the level of Ancylus Lake (approx. 65–75 m a.s.l.) previously described by Ristaniemi & Glückert (1987). The altitudes were levelled with a tachym- eter (total station), using the fixed points estab- lished by the City of Lahti and the National Land Survey of Finland as reference. For the purpose of biostratigraphical analyses, successive cores (500 mm, Ø 100–150 mm) were taken through 400 cm (110–510 cm) of the sediment using a Russian peat sampler (Jowsey 1966) at the bot- tom of the low-lying basin at 67.4 m a.s.l. Loss-on-ignition analysis (LOI) and mineral magnetic measurements (specific susceptibility) (Fig. 5) were carried out to examine the changes in sediment organic content and possible chang- es in sedimentary environments. Both LOI and specific susceptibility were analysed at 5 cm in- tervals. Susceptibility measurements were carried out on individual subsamples with MS2B equip- ment, and the results are presented as specific susceptibility χ (μm–3 kg–1). Pollen analysis (Fig. 6) was carried out to ex- amine major changes in vegetation history of the area and the results were compared with the dat- ing results of the main pollen zone assemblage boundaries of the area (Donner 1971; Donner et al. 1978). Pollen preparations were made at 10– 20 cm intervals with standard chemical methods (e.g., KOH, HF and acetolysis) (e.g., Moore et al. 1991). From each preparation at least 200 grains of pollens or spores were counted. The pollen nomenclature follows Moore et al. (1991) with the exception of Dryopteris-type, which corresponds to the Polypodiaceae taxon presented by Moore et al. (1991). The pollen zone boundaries present- ed as a reference in the pollen diagram are based 90 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander Fig. 3. An ancient shoreline (a wave-cut scarp) representing the Ancylus limit at 70.8– 72.6 m a.s.l. south of Renko- mäki Hill. (Photo: Tommi Sir- viö). Fig. 4. Cross-sectional profile of the current threshold of the Pennala basin located at 66.6– 69.4 m a.s.l. The investigated shore levels of Ancylus Lake (ca. 71.0 m a.s.l.) and the an- cient Pennala Lake (ca. 68.5 m a.s.l.) are also presented. Conventional radiocarbon dates (14C yr BP) of the shore level fluctuations are based on the analysed Pennala core. The theoretical minimum wa- ter level of the Yoldia Sea in the area and a recent landslide scar with toe formation are presented in the profile with grey dotted line and black bro- ken line, respectively. on Holocene regional pollen-assemblage zones of Southern Finland (Donner 1971; Tolonen & Ru- uhijärvi 1976; Donner et al. 1978), which in the Työtjärvi Lake and Varrassuo bog have been dat- ed as follows: the upper boundary of the Betula zone (P°) at 9000 14C yr BP (ca. 10200 cal yr BP), and the upper boundary of the Pinus zone (A°) at 8600 14C yr BP (ca. 9500 cal yr BP). The rise of Picea (Pc°) at 4200 14C yr BP (ca. 4800 cal yr BP) (Donner et al. 1978) and Tilia (T°) at ca. 7500– 7000 14C yr BP (ca. 8300–7800 cal yr BP) (e.g., Hyvärinen 1980) are also presented in the pollen diagram. In order to identify major shore-level changes in the area the core was subsampled at 10–20 cm intervals for diatom analysis (Fig. 7). Organic ma- terial was dispersed with 10% H 2 O 2 solution, af- ter which the fine mineral fraction was removed by settling. Diatoms were separated from the coarse mineral fraction by rotation method (Vuo- rela & Eronen 1978). Naphrax® was used as the mounting medium (refraction index 1.74). From each preparation 250–300 diatoms were calcu- lated except when the preparations were poor in diatoms. In the two uppermost samples (110 cm and 120 cm) diatoms were too scarce to be in- cluded into the diagram. Identification of the spe- cies was based mainly on Krammer & Lange-Ber- talot (1986, 1988, 1991a,b) and Forsström (1999). Pollen and diatom diagrams were both prepared with the TILIA and TILIA-GRAPH (version 2.0.b5) software (Grimm 1990). FENNIA 181: 1 (2003) 91Holocene development of the Pennala basin with special … Three radiocarbon dates (Table 1) were ob- tained from selected samples. The ages are given as conventional radiocarbon dates (14C yr BP) and as calibrated to calendar years (cal yr BP and cal yr BC; Stuiver & Reimer 1993; CALIB rev 4.3). The two uppermost samples (130 cm and 255–260 cm) consisted of the bulk material and were sub- jected to conventional dating (Hel-4550 & Hel- 4552). The lowest sample consisted of a well-pre- served Betula catkin scale sieved from the depth 450–455 cm and was dated with AMS technique (Hela-520). The samples were pre-treated using standard methods and dated in the Dating Labo- ratory at the University of Helsinki. Results Raised shores and the threshold of the Pennala basin Twelve observations of raised shorelines were sur- veyed for the purpose of defining the extent and maximum limit of the Ancylus transgression and the ancient Pennala Lake in the area (see Fig. 1). Eight observations provide evidence of the Ancy- lus limit in the area, whereas four shore forma- tions are assumed to be related to the ancient Pen- nala Lake. Raised shore formations typical for es- kers and till formations (e.g., Sirviö 2000) were not found in the area. Fine soils together with small fetch area at the level of the Ancylus limit appear to have effectively suppressed the forma- tion of shore marks, with only few exceptions. Ag- ricultural activities have further smoothened and destroyed some of the old shore marks since fields typically extend above the Ancylus limit. A re- markable shore formation (Fig. 3) related to the Ancylus transgression was surveyed at several lo- cations south of Renkomäki hill 1–3 km northwest from the Pennala threshold. This approximately 3 km long arched wave-cut scarp is highest at the north-western corner of the formation (70.8–72.6 m a.s.l.). Three other shore formations (small, partly disturbed wave-cut scarps), also related to the Ancylus transgression, were found at the Fig. 5. Sediment lithostratigraphy of the Pennala core: Loss-on-ignition analysis and specific susceptibility with radiocarbon dating results and reference to the diatom zones (D.Z.) (for further details, see the text). 92 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander Fig. 6. Core description (symbols as in fig. 5) and pollen stratigraphy of the Pennala core with radiocarbon dating results and reference to the Pinus (P°) and Alnus (A°) pollen assemblage zone boundaries. The rise of Tilia (T°) and Picea (Pc°) limits are also presented. FENNIA 181: 1 (2003) 93Holocene development of the Pennala basin with special … Fig. 7. Core description (symbols as in fig. 5), diatom stratigraphy (selected species) and diatom zones of the Pennala core with radiocarbon dating results. 94 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander northern part of the Pennala basin at 70.8– 71.5 m a.s.l. The level of the ancient Pennala Lake was sur- veyed in the northern part of the basin at four lo- cations with wave-cut scarps. The altitudes of the shore marks varied between 67.9 and 68.4 m a.s.l. Some of the shore formations had been partly dis- turbed by agricultural activities, and the most re- liable results were obtained from undisturbed shore marks (68.3–68.4 m a.s.l.) adjacent to the Uusitalo and Alestalo dwelling sites. The same lev- el of the ancient Pennala Lake was observed in the form of a clear shift from highly organic soils of peat and gyttja to minerogenic clayish soils throughout the Pennala basin below 70 m a.s.l. A cross-sectional profile of the threshold of the basin in the north-west was surveyed (Fig. 4). The Rengonjoki River has cut a 5 m deep channel through the clayish soil at the threshold, and the narrow channel has been subsequently re-worked by landslides. The altitude of the current thresh- old varies between 66.6–69.4 m a.s.l., as meas- ured from the current water level of the Rengon- joki River to the break of slope at the side of the channel. LOI, susceptibility measurements and radiocarbon dates The lithostratigraphy of the Pennala basin was de- scribed in detail with the aid of loss-on-ignition (LOI) analysis, susceptibility measurements, radi- ocarbon dates and pollen and diatom analysis. The general lithostratigraphy of the Pennala core (Fig. 5) from the bottom to the top is as follows: 510–210 cm clay gyttja, 210–155 cm fine detri- tus gyttja, 155–125 cm coarse detritus gyttja and 125–110 cm Carex peat (110–0 cm not analysed). Together with the increasing LOI towards the top of the core, the corresponding susceptibility values show a clear decreasing trend with a few exceptions. In the basal part of the core (510–395 cm), the susceptibility values vary between 0.094–0.133 μm–3kg–1 with the highest value at 455 cm. As the radiocarbon age 9290 ± 125 14C yr BP (10450 cal yr BP) (Hela-520) (455–460 cm) suggests, the increase in susceptibility values probably corresponds to a rise in water level due to the Ancylus transgression, whereas the subse- quent decrease in susceptibility values is connect- ed to the isolated Pennala Lake phase. These changes in the susceptibility values are not du- plicated in the LOI values, which vary between 6.3 and 7.9% at same level without showing any significant trend. Another clearly defined break in the decreas- ing trend of susceptibility values is observed at the depth of 320–285 cm, where the susceptibility of the samples increases from 0.038 up to 0.051 μm–3kg–1. The higher susceptibility values are fol- lowed by a slight increase (9.8–18.6%) in LOI at 290–255 cm. Based on the radiocarbon age 6210 ± 70 14C yr BP (7100 cal yr BP) (Hel-4552) ob- tained from the level 255–260 cm, the decrease in susceptibility and the local peak value of LOI coincide with the climatic optimum (e.g., Eronen 1990) during the Atlantic chronozone. Towards the top of the core the susceptibility values approach zero together with a sharp in- crease in LOI. This is believed to represent the fi- nal overgrowth of the Pennala Lake, dated at 2930 ± 90 14C yr BP (3120 cal yr BP) (Hel-4550) at the depth of 130 cm. Pollen stratigraphy The general features in the pollen stratigraphy (Fig. 6) can be described in terms of regional pol- len assemblage zones for Southern Finland (Don- ner 1971; Donner et al. 1978). References are also made to the Flandrian chronozones present- ed by Mangerud et al. (1974). The basal section of the core belongs to the Betula zone corresponding closely to the Prebo- Table 1. Radiocarbon dating results of the Pennala core. FENNIA 181: 1 (2003) 95Holocene development of the Pennala basin with special … real chronozone 10000–9000 14C yr BP (ca. 11500–10200 cal yr BP). This is followed by short period of Pinus zone corresponding to the Boreal chronozone 9000–8000 14C yr BP (ca. 10200– 8900 cal yr BP). Except for trees and shrubs, herbs dominate the lowermost section. Gramineae, Cy- peraceae, Filipendula and spores of Equisetum are abundant. The aquatic pollen in the basal part of the core is dominated by Potamogeton, Nym- phaea and Sparganium. The upper boundaries of Betula (P°) and Betula-Alnus-Corylus-Ulmus (A°) zones are defined by the rational limit for the rise of Pinus and Alnus, respectively, though in the Pennala core the Pinus limit (P°) is not very dis- tinct. Together with the two other radiocarbon dates, the date obtained from the middle of the Pinus zone (9290 ± 190 14C yr BP; Hela-520) al- lowed preparation of an age-depth curve with a 2nd order polynomial line fitting function. Based on the curve, the rise of Pinus has taken place at ca. 9450 14C yr BP (ca. 10700 cal yr BP) and the rise of Alnus at ca. 9150 14C yr BP (ca. 10200 cal yr BP). The uppermost part of the core belongs to Bet- ula-Alnus-Corylus-Ulmus zone and the Atlantic and Subboreal chronozones 8000–2500 14C yr BP (ca. 8900–2600 cal yr BP). Pollen of Betula, Pi- nus and Alnus dominate the zone. Relative pro- portions of Corylus and Ulmus remain constant and the total proportion of the pollen of trees and shrubs are at their maximum level throughout the zone. Two clearly detectable reference points on the diagram for the Atlantic and Subboreal chronozones include the rise of Tilia at 320 cm (T°) ca. 7200 14C yr BP (ca. 8000 cal yr BP) and the rise of Picea at 180 cm (Pc°) ca. 4300 14C yr BP (ca. 4900 cal yr BP). Both of these are in good agreement with the typical radiocarbon dates pre- viously presented for T° (e.g., Hyvärinen 1980) and Pc° limits (e.g., Donner et al. 1978). Above the Picea limit (Pc°) the proportions of both herbs and aquatic plants increase consider- ably, as shown by the rise of Cyperaceae, Gramineae and Potamogeton curves. At the same time, the relative proportions of tree species show wide fluctuations, such as the abrupt rise of Pi- nus and Alnus in the uppermost samples of the core. The radiocarbon date 2930 ± 90 14C yr BP (Hel-4550) obtained from the upper limit of aquatic plants indicates the final drying up of the lake directly after the dated level. Diatom stratigraphy The sediments were analysed for diatoms in or- der to determine the main phases of the develop- ment of Pennala basin, including the possible Ancylus transgression, the stages of isolation, and the final overgrowth. The diatom diagram (Fig. 7) can be divided into three sections: the small lake/ Ancylus Lake stage (diatom zones Ia & Ib), the small lake stage (diatom zone II) and the over- growth stage (diatom zone III). The uppermost part of the core was poor in diatoms and represents terrestric mire environment based on other litho- and biostratigraphic evidence. The flora of the lowermost diatom zone Ia (510–470 cm) consists mainly of meroplanctonic Aulacoseira granulata (40–60%) and A. ambigua, plus genus Epithemia, with lesser proportions of species Cymbella aspera, Cyclostephanos dubi- us, Cyclotella radiosa, Synedra capitata, Synedra ulna and genera Eunotia, Pinnularia and Cymbel- la. At the bottom of the diatom zone Ib (470–400 cm), the relative proportions of Aulacoseira gran- ulata decline abruptly, while the relative propor- tions of mainly epiphytic and benthic species be- gin to increase. These include Cymbella aspera and genera Epithemia, Pinnularia and Eunotia. The following diatoms found from this zone be- long to the flora typically observed in the Ancy- lus Lake sediments (e.g., Tynni 1969; Eronen 1976; Ignatius & Tynni 1978; Ristaniemi 1984): Aulacoseira islandica, Cymatopleura elliptica var. hibernica, Cymbella aspera, C. prostata, Surirella capronii, Gyrosigma attenuatum, G. acuminatum, Amphora ovalis and genus Epithemia. In addition to these typical Ancylus Lake species the follow- ing taxa are also present in the diatom zone Ib: Cyclostephanos dubius, Cyclotella radiosa, Syn- edra capitata, S. ulna, Cocconeis pediculus, C. placentula, Aulacoseira granulata, A. ambigua, Amphora libyca, Stauroneis phoenicenteron, Rho- palodia gibba, and genera Cymbella and Surirel- la. The boundary between diatom zones Ib and II is marked by a sharp increase in Aulacoseira gran- ulata and A. ambigua species and a sharp decline in Epithemia spp. starting at around 420 cm with a clear indication of the final environmental change at ca. 400 cm. The fresh-water meroplanc- tonic Aulacoseira ambigua and A. granulata have high proportions (20–70%) throughout the diatom zone II (400–170 cm). Other species that occur 96 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander through diatom zone II, although with rather small proportions, include Cyclostephanos dubius, Cy- clotella radiosa, Gyrosigma acuminatum, Tabel- laria fenestrata, T. flocculosa, Nitzschia sigmoi- dea, N. levidensis var. victoriae, Cyclotella meneghiniana, Cyclotella stelligera, Stauroneis phoenicenteron and Navicula americana. Contra- ry to the lower diatom zone, the genera Eunotia, Surirella and Epithemia are poorly presented here. At the top of this zone, genus Fragilaria begins to increase simultaneously with the sediment change from clay gyttja to fine gyttja. Diatom zone III (170–130 cm) consists mainly of species Aulacoseira italica, A. subarctica, A. pfaffiana, A. lacustris, A. lirata, Tabellaria fenes- trata, T. flocculosa, Tetracyclus glans and genera Pinnularia, Gomphonema, Eunotia and Fragilar- ia, which are typical to small lake conditions (e.g., Hyvärinen 1999). Diatom fauna found in the up- permost coarse gyttja bed represents the final phase of lowering water level and drying up of the ancient Pennala Lake. The overlying Carex peat (120–110 cm) was too poor in diatoms to be presented in the diagram. The presented results of diatom analysis are in good agreement with the pollen and LOI analysis described earlier. Discussion and Conclusions The current study gives new information on the Holocene development of the Pennala basin with reference to the Ancylus transgression, the ancient Pennala Lake, and the dated Stone Age dwelling sites in the area. The main conclusions from the Pennala site studied can be summarized as fol- lows (Fig. 8): 1) The basal part of the studied core includes a possible small lake phase of the Pen- Fig. 8. Age-depth distribution curve (2nd order polynomial line fitting) with reference to the development of the Pennala basin. Also included are summaries of archaeologically relevant dating results in the Pennala basin (bold/italic) (Meinander 1960, 1971; Vuorela 1981; Poutiainen 2002) and in the nearby environments (Donner et al. 1978; Matiskainen 1989b) together with the main cultural stages (Siiriäinen 1982; Matiskainen 1989a). FENNIA 181: 1 (2003) 97Holocene development of the Pennala basin with special … nala basin at the end of regressive stage of Yoldia Sea, 2) the Ancylus transgression started at ca. 9600 yr 14C BP (10900 cal yr BP) and the final isolation occurred around 8900 yr 14C BP (10000 cal yr BP) during the regressive stage of Ancylus Lake, and 3) the final isolation from the Baltic Sea was followed by a long-term lake phase which lasted until ca. 2900 yr 14C BP (3000 cal yr BP), when the Pennala basin turned to a terrestric mire. The interpretation of the basal part of the core – as representing an isolated, small lake phase of the Pennala basin from the Yoldia Sea until the Ancylus transgression – remains questionable. The upper boundary of the lowermost diatom zone Ia is marked by a sharp decrease in the proportion of Aulacoseira granulata, which may indicate small lake conditions before the transgression. The beginning of the small lake phase, however, is ambiguous, as the horizon of the isolation from the Yoldia Sea was not represented in the core. The slight increase of typical Ancylus Lake spe- cies at the boundary between diatom zones Ia and Ib suggests that Pennala basin became a part of the Ancylus Lake. The approximate age for the lower limit of the diatom zone Ib (based on the 2nd order polynomial age-depth curve) suggests that the Pennala basin became a part of Ancylus Lake at ca. 9600 14C yr BP (ca. 10900 cal yr BP), which is confirmed by the radiocarbon date 9290 ± 190 14C yr BP (Hela-520) obtained from slight- ly above the maximum occurrence of Epithemia spp. at 460 cm. The given radiocarbon date is in good agreement with the dates of the Ancylus transgression presented previously (e.g., Ristanie- mi & Glückert 1987). The evidence of the transgression is supported by the fluctuations observed in the magnetic sus- ceptibility (Fig. 5) at the level of the assumed transgression. The variation and slight increase in the susceptibility in the diatom zone represent- ing Ancylus Lake is probably a consequence of increased erosion on the shores of the Ancylus Lake caused by water level fluctuations during the transgression. A similar susceptibility pattern has been reported from the Lake Babinskoye (Inger- manland, Russia) sediments during the Litorina transgression and explained by increased erosion on the shores (Miettinen 2002). Sandgren et al. (1990), however, have presented opposing results from the Lake Ådran (eastern Sweden), where the regressive phase of the Ancylus Lake is marked by an increase in susceptibility values, whereas the Litorina transgression coincided with low sus- ceptibility values. The high susceptibility values during the regressive phase were explained as being induced by increased erosion. Low suscep- tibility values during the Litorina transgression were explained by dissolution of ferromagnetic minerals in brackish-marine water (Snowball & Thompson 1988). The relatively poor diatom evidence of the sug- gested small lake stage and the following Ancy- lus transgression are most rationally explained by the location of both the Pennala basin and its threshold. As shown in Fig. 1, the Pennala basin formed a sheltered bay during the Ancylus trans- gression, and was connected to more open areas of Ancylus Lake at Näkkimistö by 800 m long and 200 m wide strait. The whole Porvoonjoki River valley was connected to the more open Ancylus Lake by several narrow straits. This might have re- sulted in ecological conditions typical for small lakes or shallow bays showing diatom diagrams dominated by Epithemia spp. with only a slight rise in the curves of other typical Ancylus Lake species (e.g., Aulacoseira islandica and Gyrosig- ma attenuatum). As seen in Fig. 4, the Pennala threshold has been cut down to clayish soil by several metres whereas the upper value given for the threshold (69.4 m a.s.l.) together with the shoreline measurements suggest only a minor (probably 1.5–2 m) rise in the water level (up to 71–71.5 m a.s.l.) (Fig. 4) and small changes in ecological conditions in the area during the An- cylus transgression. Since the Pennala basin is a part of a greater drainage basin, the relatively poor diatom evi- dence of transgression might be also due to mix- ing of sediments, and deposition of material de- rived from the upper Pihlajasuo bog area, where the independent small lake might have been iso- lated during the late regressive stages of the Yol- dia Sea. Concurrence of the typical small lake flo- ra of Pinnularia and Eunotia spp. with typical An- cylus Lake species at diatom zone Ib might be explained by erosion and re-deposition of sedi- ment originally deposited during the small lake phase as the transgression proceeded. Discrepancies were observed within the pollen analysis, where the limits of pollen assemblage zones of Pinus (P°) and Alnus (A°) almost overlap and show distinctively older ages (ca. 450 and 550 14C yr, respectively) than previously present- ed by Donner et al. (1978). However, similar dif- ferences have been observed elsewhere (e.g., Hy- värinen 1980), and radiocarbon dates obtained 98 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander from the P° and A° limits in Southern Finland typ- ically show regional differences (e.g., Donner et al. 1978; Ristaniemi & Glückert 1987). The older ages observed here for the limits might be ex- plained by changes in the local palaeoenviron- ment adjacent to the Pennala basin, which would have encouraged the early spread of both Pinus (due to proximity to gravelly and sandy fluviogla- cial formations) and Alnus (due to emergence of new shoreline during the Ancylus regression). Since the lowermost radiocarbon date (9290 ± 125 14C yr BP) was obtained from a single Betula catkin scale, there is always the possibility that this is a secondary deposit and that a dating of the primary deposits of the core would result to younger dates for both the P° and A° limits, and the Ancylus transgression. The Ancylus lake phase ended in the Pennala basin at ca. 8900 14C yr BP (ca. 10000 cal yr BP) leading to the final isolation of the Pennala basin from the Baltic Sea. According to the currently an- alysed pollen and diatoms and earlier studies (Vuorela 1981), the ancient Pennala Lake can be described as shallow, eutrophic and alkaliphilous lake, as Aulacoseira granulata and A. ambigua di- atom species have been typically found in small lakes indicating alkaliphilous eutrophic condi- tions (e.g., Korhola 1990b). This interpretation gains support also from the pollen analyses and the well-known presence of Trapa natans (Aalto 1981; Vuorela 1981), which typically favours such ecological conditions. The evidence of possible water level fluctua- tions in the ancient Pennala Lake during the mid- dle of the lake phase is scarce. The most distinct piece of evidence of a potential high water level is the clear rise in the susceptibility values during the Atlantic period at ca. 7000–6500 14C yr BP (ca. 7800–7400 cal yr BP). The significant varia- tion in the proportions of Aulacoseira species re- mains unexplained and might be related to water level fluctuations as these changes correspond to the changes in the susceptibility measurements (the peak of Aulacoseira granulata at 280 cm co- incides with high susceptibility). It has to be not- ed, that high water levels have been observed in many small lakes during humid Atlantic period (e.g., Donner et al. 1978; Donner 1995), and sev- eral authors have suggested that the low water lev- el in lakes and mires was due to a cool and dry climate during the following Subboreal period (Korhola 1990b). In many cases, this might have accelerated the final overgrowth of lakes in South- ern Finland during the early Subboreal period (Korhola 1990a). The absolute shore levels of pos- sible fluctuations in the ancient Pennala Lake re- main undetermined since only one distinctive an- cient shoreline level has been detected at ca. 68.5 m a.s.l. The final phase in the history of the Pennala Lake is marked by clear changes in both diatom and pollen stratigraphy dated close to the Picea limit (Pc°) during the early Subboreal period at 4000 14C yr BP (ca. 4500 cal yr BP). At this time, the relative proportions of small lake diatom spe- cies, and pollen of aquatic plants, increased abruptly. The abrupt increase in LOI also marks the change. The open area and the extent of the Pennala Lake may have decreased significantly during this stage. These observed changes clearly indicate overgrowth, lowering water depth, and decreasing extent of the lake. Paludification led to final overgrowth of the ancient Pennala Lake during the late Subboreal period at 2900 14C yr BP (ca. 3000 cal yr BP), after which the basin transformed to a terrestric mire. Further develop- ment of the Pennala basin as a mire was not in- vestigated. The dated archaeological data (Fig. 8) demon- strates that specific absolute dates for the Early Mesolithic dwelling sites in the area – during which the Pennala basin was a sheltered bay of the Ancylus Lake – are still scarce. The dwelling sites in Pennala basin have been inhabited most- ly during the Neolithic period at ca. 5500–3500 14C yr BP (ca. 6300–3800 cal yr BP). In this peri- od, the Pennala basin formed a small inland lake as a part of the Porvoonjoki River drainage basin. The Neolithic stage of the evidence from the dwelling sites, dated with radiocarbon method, starts during the Late Atlantic period. The poten- tial evidence of forest clearing, observed in the nearby Työtjärvi Lake (Hollola) (Donner et al. 1978) and the spread of Trapa natans into the Pen- nala Lake (Vuorela 1981), noticeably concur with the evidence of the Neolithic settlement. Earlier pollen analyses (Vuorela 1981) and analyses of macro remnants from the uppermost layers (Aal- to 1981) of the core sampled near the shoreline of the Pennala Lake correspond well with the re- sults presented in this paper on the final stages of the development of the ancient lake. The poten- tial connection between the human impact on vegetation (Vuorela 1981) and the eutrophication preceding the final overgrowth of the lake, can- not be ignored. As a conclusion, the overgrowth FENNIA 181: 1 (2003) 99Holocene development of the Pennala basin with special … of the lake has probably occurred as a result of several supporting factors, such as the Subboreal climate, the human influence and the shallow bathymetry of the lake (Tikkanen & Korhola 1993). There is still a distinctive gap between the dat- ed Early Mesolithic and Neolithic dwelling sites in the area. It is unjustifiable to use shore dis- placement of the Baltic as the basis for dating of the Mesolithic dwelling sites due to long lake phase of the Pennala basin. Similar limitations have been observed elsewhere while using shore displacement of the Baltic as a basis for prelimi- nary dating of Stone Age dwelling sites e.g., in Kanteleenjärvi (Pukkila) (Sirviö 2000), Luhdanjoki (Lahti–Hollola) (Sirviö et al. 2002) and Askola ar- eas (Matiskainen 1989b). It is, therefore, advisa- ble to take great care while applying shoreline displacement chronology of the Baltic to the dat- ing of the Mesolithic and Neolithic sites around bogs and extensive deposits of peat and gyttja, i.e. areas, where ancient lakes have potentially exist- ed. ACKNOWLEDGEMENTS This research received financial support from the Finnish Cultural Foundation. We thank anonymous referees for their comments, Prof. Matti Eronen, Prof. Matti Tikkanen, Prof. Hannu Hyvärinen and Heikki Haila, Lic.Phil., for valuable comments during the research, Dr Juhani Virkanen for help in the labora- tory, Maija Heikkilä, MSc, for grouping the pollen diagram and Minna Väliranta, MSc, for help in iden- tification of macro remnants for radiocarbon dating. We also thank Hannu Poutiainen, MA, Hannu Taka- la, MA, Lic.Phil., and other enthusiastic archaeolo- gists of the City Museum of Lahti for great help dur- ing the study. Thanks for the preliminary language corrections belong to Dr Andrew Rebeiro-Hargrave. The Dating Laboratory of the University of Helsinki provided the radiocarbon dates. REFERENCES Aalto M (1981). Vesipähkinän (Trapa natans L.) läm- pökautinen esiintyminen Pennalassa. Lahden kaupungin museo- ja taidelautakunta, Tutkimuk- sia XIX/1981, 20–25. Donner J (1971). Towards a stratigraphical division of the Finnish Quaternary. Commentationes Phys- ico-Mathematicae 41, 281–305. Donner J (1995). The Quaternary history of Scandi- navia. 200 p. Cambridge University Press. Donner J, P Alhonen, M Eronen, H Jugner & I Vuo- rela (1978). Biostratigraphy and radiocarbon dat- ing of the Holocene lake sediments of Työtjärvi and the peats in the adjoining bog Varrassuo west of Lahti in Southern Finland. Annales Botanici Fennici 15, 258–280. Eronen M (1976). A radiocarbon dated Ancylus trans- gression site in south-eastern Finland. Boreas 5, 65–76. Eronen M (1990). Muuttuva ilmasto. Terra 102, 220– 238. Eronen M & H Haila (1982). Shoreline displacement near Helsinki, southern Finland, during the An- cylus Lake stage. Annales Academiae Scientiarum Fennicae A III 134, 111–129. Forsström L (1999). Piikuoriset levät. 104 p. Oulun yliopiston geotieteiden laitos. Glückert G & O Ristaniemi (1982). The Ancylus transgression west of Helsinki, South Finland – A preliminary report. Annales Academiae Scien- tiarum Fennicae A III 134, 99–110. Glückert G (1991). The Ancylus and Litorina trans- gressions of the Baltic in southwest Finland. Qua- ternary International 9, 27–32. Grimm E (1990). Tilia and Tilia-Graph: PC Spread- sheet and graphics software for pollen data. IN- QUA Working Group on Data-Handling Meth- ods Newsletter 4. Hyvärinen H (1980). Relative sea-level changes near Helsinki, southern Finland, during Early Litorina times. Bulletin of the Geological Society of Fin- land 52, 207–219. Hyvärinen H (1999). Shore displacement and Stone Age dwelling sites near Helsinki, southern coast of Finland. In Huurre H (ed): Dig it all – papers dedicated to Ari Siiriäinen, 79–89. The Finnish Antiquarian Society & Archaological Society of Finland. Hyyppä E (1937). Post-glacial changes of shore-line in South Finland. Bulletin de la Commission Géologique de Finlande 120, 1–225. Hyyppä E (1943). Beiträge zur Kenntnis der Ladoga- und Ancylustransgression. Bulletin de la Commis- sion Géologique de Finlande 128, 139–178. Ignatius H & R Tynni (1978). Itämeren vaiheet ja pii- levätutkimus. Publications of the Department of Quaternary Geology 36, 1–26, University of Tur- ku. Itkonen TI (1949). Muinaissuksia ja -jalaksia. Suo- men Museo 1949, 27–40. Jantunen T (1995). A late Litorina transgression in the District of Porvoo in southern Finland. Annales Academiae Scientiarum Fennicae A III 158, 1–40. Jowsey PC (1966). An improved peat sampler. New Phytologist 65, 245–248. Korhola A (1990a). Suomen soiden synty ja kehitys. Terra 102, 256–267. Korhola A (1990b). Paleolimnology and hydroseral development of the Kotasuo bog, southern Fin- land, with special reference to the Cladocera. Annales Academiae Scientiarum Fennicae A III 155, 1–40. 100 FENNIA 181: 1 (2003)Tommi Sirviö and Meri Kajander Krammer K & H Lange-Bertalot (1986). Bacillario- phyceae 1. In Ettl H, J Gerloff, H Heynig & D Mollenhauer (eds). Süsswasserflora von Mittel- europa 2/1. 876 p. Gustav Fischer Verlag, Stutt- gart, New York. Krammer K & H Lange-Bertalot (1988). Bacillario- phyceae 2. In Ettl H, Gerloff J, Heynig H & D Mollenhauer (eds). Süsswasserflora von Mittel- europa 2/2. 596 p. Gustav Fischer Verlag, Stutt- gart, New York. Krammer K & H Lange-Bertalot (1991a). Bacillario- phyceae 3. In Ettl H, J Gerloff, H Heynig & D Mollenhauer (eds). Süsswasserflora von Mittel- europa 2/3. 576 p. Gustav Fischer Verlag, Stutt- gart, New York. Krammer K & H Lange-Bertalot (1991b). Bacillario- phyceae 4. In Ettl H, J Gerloff, H Heynig & D Mollenhauer (eds). Süsswasserflora von Mittel- europa 2/4. 437 p. Gustav Fischer Verlag, Stutt- gart, New York. Luho V (1950). Kertomus Orimattilan Pennalan kivi- kautisen löytöpaikan kaivauksesta. Unpublished Excavation report. Lahden kaupunginmuseo/Päi- jät-Hämeen maakuntamuseo. Mangerud J, Andersen ST, Berglund B & J Donner (1974). Quaternary stratigraphy of Norden, pro- posal for terminology and classification. Boreas 3, 109–128. Matiskainen H (1989a). The Chronology of the Finn- ish Mesolithic. Iskos 8, 379–390. Matiskainen H (1989b). The paleoenvironment of Askola, southern Finland. Mesolithic settle- ment and subsistence 10000–6000 BP. Iskos 8, 1–97. Meinander CF (1960). Kaivauskertomus – C.F. Mein- anderin kaivaus Orimattilan Pennalassa 2.– 4.6.1959. Unpublished excavation report. Meinander CF (1971). Radiokarbondateringar till Finlands stenÂlder. Societas Scientiarum Fenni- ca Årsbok 47 B (5), 1–14. Miettinen A (2002). Relative sea level changes in the eastern part of the Gulf of Finland during the last 8000 years. Annales Academiae Scientiarum Fen- nicae, Geologica-Geographica 162, 1–102. Moore P, JA Webb & ME Collinson (1991). Pollen analysis. 2nd ed. 216 p. Blackwell, Cambridge. Poutiainen H (1998). Porvoonjoen vesistöalueen ki- vikautisen asutuksen arkeologinen inventointi – Hollolan, Lahden ja Orimattilan alueella. 22 p. Inventory report. Lahden kaupunginmuseo/Päijät- Hämeen maakuntamuseo. Poutiainen H (2001). Lahti Myllyoja, Kivikautisen asuinpaikan arkeologinen koekaivaus. 26 p. Ex- cavation report. Lahden kaupunginmuseo/Päijät- Hämeen maakuntamuseo. Poutiainen H (2002). Personal communication 05.09.2002. Poutiainen H & H Takala (2001). Rengonjoen arkeo- loginen inventointi Lahden ja Orimattilan rajal- la. 15 p. Inventory report. Lahden kaupunginmu- seo/Päijät-Hämeen maakuntamuseo. Ristaniemi O (1984). Ancylusjärven aikainen rannan- siirtyminen Salpausselkä-vyöhykkeessä Karjaloh- jan–Kiskon alueella Lounais-Suomessa. Publica- tions of the Department of Quaternary Geology 53. University of Turku 75 p. Ristaniemi O & G Glückert (1987). The Ancylus transgression in the area of Espoo – The First Sal- pausselkä, southern Finland. Bulletin of the Ge- ological Society of Finland 59 Part I, 45–69. Sandgren P, Risberg J & R Thompson (1990). Mag- netic susceptibility in sediment records of Lake Ådran, eastern Sweden: correlation among cores and interpretation. Journal of Paleolimnology 3, 129–141. Siiriäinen A (1973). Studies relating to shore dis- placement and Stone age Chronology in Finland. Finskt Museum 1973, 5–22. Siiriäinen A (1982). Shore displacement and archae- ology in Finland. Annales Academiae Scientiarum Fennicae A III 134, 173–184. Siiriäinen A (1987). On archaeology and land uplift in Finland. Geological Survey of Finland, Special Paper 2, 43–45. Sirviö T (2000). Kivikautisten asuinpaikkojen sijainti suhteessa Itämereen Pukkilanharjun, Kanteleen ja Luhdanjoen alueilla. 40 p. Research report. Lah- den kaupunginmuseo/Päijät-Hämeen maakunta- museo. Sirviö T, M Kajander & M Heikkilä (2002). Ancylus transgressio ja pienvesistöjen kehitys Lahden– Orimattilan alueella. 49 p. Research report. Lah- den kaupunginmuseo/ Päijät-Hämeen maakunta- museo. Snowball I & R Thompson (1988). The occurrence of Greigite in sediments from Loch Lomond. Jour- nal of Quaternary Science 3, 121–125. Stuiver M & P Reimer (1993). Extended 14C database and revised CALIB 3.2 14C age calibration pro- gram. Radiocarbon 35, 215–230. Takala H (1999). Arkeologiset tutkimukset Lahden Ristolassa 1999. Excavation report. Lahden kau- punginmuseo/Päijät-Hämeen maakuntamuseo. Takala H (2001). Lahti, Renkomäki, Uusitalo ja Ori- mattila, Pennala, Alestalo – Arkeologinen koekai- vaus. 26 p. Excavation report. Lahden kaupun- ginmuseo/Päijät-Hämeen maakuntamuseo. Takala H (2002). Personal communication 01.09. 2002. Tikkanen M & A Korhola (1993). Divergent succes- sions in two adjacent rocky basins in southern Finland: A physiographic and palaeoecological evaluation. Annales Academiae Scientiarum Fen- nicae A III 157, 1–26. Tolonen K & R Ruuhijärvi (1976). Standard pollen diagrams from Salpausselkä region of southern Finland. Annales Botanici Fennici 13, 155–196. Tynni R (1966). Über spat- und postglaziale Uferver- schiebung in der Gegend von Askola, Südfinn- land. Bulletin de la Commission Géologique de Finlande 223, 97 p. Tynni R (1969). Suomen yleisimmät piilevät sekä in- FENNIA 181: 1 (2003) 101Holocene development of the Pennala basin with special … dikaattorilajit. 15 p. Turun yliopiston maaperä- geologian laitos. Valovirta V (1949). Orimattilasta löydetyn reenjalak- sen ikä. Geologi 3–4, 10–11. Vuorela I (1978). Local settlement history of the Lahti area as shown by pollen analysis. Bulletin of Ge- ological Society of Finland 50, 45–57. Vuorela I (1981). Pennalan kivikautisen asuinpaikan siitepölystratigrafia. Lahden kaupungin museo- ja taidelautakunta, Tutkimuksia XIX/1981, 1–19. Vuorela I & M Eronen (1978). Suomen Kvartääripa- leontologian yleiset perusteet ja menetelmät. Geologian ja paleontologian osasto. Helsingin yliopisto.