Morphologisch-stratigraphische Grundzüge des östlichen Salpausselkä-Gebiets

Abstract

The present study is concerned with some aspects of the Quaternary history of the eastern parts of the Salpausselkä region. The most prominent features of the Salpausselkä marginal formation are the glaciofluvial deltas and the hill and kettle topography in the high proximal parts. Till layers have been found on top of sorted material in some of the sections through the proximal parts. Oscillation of the ice margin has lefts marks also in the terrain between the Salpausselkäs. The orientation and distribution of glaciofluvial formations, and especially of eskers has been to a large extent governed by bedrock tectonics. The oldest organic sediments from two bogs have been dated. According to C14 determinations the Koivusilta bog basin, between the First and Second Salpausselkä, was occupied by a lake 8250 ± 300 yrs B.C. corresponding to the end of the Younger Dryas-period. Fine sand containing Bryales- peat was deposited 8150 + 400 yrs B.C. in a bog pond in Eräjärvi 2 kilometers north of the 2nd. Salpausselkä. The decrease in organic content after this period was observed in three core samples, being probably due to the deterioration of the climate during the transition from the Younger Dryas to the Preboreal period. It corresponds to the Preboreal climatic deterioration in Central European zonation.