Glacial geomorphology and dynamics in Soviet Karelia interpreted by means of satellite imagery

Abstract

The glacial geomorphology of Soviet Karelia was mapped using Landsat satellite imagery. The data of the multispectral scanner were processed using the photographic image enhancement and color combination tech­nique for visual interpretation. Glaciofluvial landforms, streamlined forma­tions, end moraines and hummocky moraine tracts were mapped, along with the type and amount of glacial erosion. As a result of the work, the glaciomorphological data were greatly increased compared with maps avail­able earlier. The direction and strength of the glacial flow and the stages of deglaciation were interpreted on the basis of the maps compiled. Con­clusions were drawn as to the thermal regime of the ice sheet and the rela­tions between the glacial dynamics and morphology.

During the Alleröd Substage, the main direction of the glacial flow was from the northwest, running radially from the Scandinavian mountain range. Later, the direction shifted about 30' more to the west, with the dome being situated in northern Sweden. Locally, near the interlobate zones, the flow shifted as much as 90'. The existence of the oriented elements representing earlier and later flow directions in any area supports the theory that the ice sheet had a melting bed in at least two different zones during the deglacia­tion. These zones were probably time‑transgressive when the volume of the ice sheet diminished.

Extensive marginal formations, evidently belonging to the Salpausselkä (Younger Dryas) Substage, were discovered. The ice margin was situated during the First Salpausselkä phase near the present White Sea coast. In the areas of the active ice lobes, there exist fan‑shaped drumlin fields and landscapes of intensive areal scouring. Between the lobes, there occur re­markable glaciofluvial interlobate formations, like the Kalevala and Syam­ozero complexes. In the interlobate areas, hummocky and transverse moraines are common and streamlined formations as well as landscapes of glacial erosion are rare. The glacial dynamics of the ice sheet during the deglaciation clearly controls the occurrence of different types of glacial land­forms. Most of the forms were generated beneath constantly streaming ice in a zone of some hundred kilometers from the receding ice margin.