On deglaciation in Southern and Western Finland

Abstract

The purpose of this study was to analyze the stages of deglaciation in southern and western Finland as well as in the Gulf of Bothnia. The positions of the continental ice sheet were determined in the light of the evidence provided by various end moraines, notably so‑called De Geer moraines. The findings were based on the interpretation of aerial photographs and topographic maps as well as on first‑hand investigations in the field. The earlier view of the deglaciation in the region covered proved to be correct, in the main, but revisions had to be made in certain details. The most important of the results involving changes were the following: 1) The continental ice sheet receded between the coast of the Gulf of Finland and the SalpausseIkä systems toward the northwest maintaining a straight front. No bend corresponding to the great bend in Sal­pausselkä I existed in the ice margin during this stage. The bend in the ice margin formed as it re‑advanced later to Salpausselkä 1. 2) No long and narrow glacial bay existed in the region of Lake Päijänne. 3) Hämeenkangas, the Näsi­järvi formation and the Jyväskylä esker developed at the edge of the glacier synchronously, forming a bipartite end‑moraine are. 4) In the region of Etelä-­Pohjamnaa (South Bothnia) and in the Quarken (Merenkurkku), the ice sheet retreated in a northwesterly direction. The ice margin did not cross the Quarken in a northwest‑southeast line. 5) In the great open stretch of the Gulf of Bothnia (= Bothnian Sea), there never existed a big glacial estuary – instead there was a great ice lobe.