The Early Postglacial History of Lake Sirkkajärvi, Southern Finland, with Implications to the “G Stage” of the Baltic

ABSTRACT

Radiocarbon-dated basal sediments of the highest lake in southern Finland, Sirkkajärvi (131.9 m a.s.l.), were studied for organic content, pollen and diatoms in order to follow early developmental phases of the lake, and by inference, Late Weichselian water level changes in the Baltic. The lake became isolated during the final drainage of the Baltic Ice Lake about 10,300 ¹⁴C years BP. Pollen and diatom analyses show typical developmental features from the earliest Holocene onwards, including rapid afforestation and progressive natural acidification. No traces of the hypothesised low water stage, g, were found in the sedimentary sequence studied, although the site and its surrounding should have been above the Baltic Ice Lake during this stage. This is in agreement with recent implications based on morphological evidence. Finally, the uncertainties associated with the approach are discussed.