Holocene development of the Pennala basin with special reference to the palaeoenvironment of Meso- and Neolithic dwelling sites, Lahti–Orimattila, Southern Finland

Abstract

The Holocene development of the Pennala basin, Southern Finland, was studied using lithostratigraphical and biostratigraphical methods, shore level surveys and radiocarbon dating in the areas adjacent to the I Salpausselkä icemarginal
formation. The study results give an improved picture of the shoreline displacement and palaeoenvironment of the Pennala basin during the period of 10000–2500 14C yr BP (ca. 11400–2600 cal yr BP).

The results indicate that the Ancylus Lake stage in the Pennala basin occurred during the Preboreal and Early Boreal chronozones around 9600–8900 14C yr BP (ca. 10900–10000 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 located 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.