Age and Position of the Maximum Boundary of the Scandinavian Ice Sheet in the Valdai (Weichselian, Vistulian) Glaciation and Relief in the Peripheral Area of the Ice Sheet

After the end of the Mikulino interglacial, in connection with the increasing cooling trend, the Scandinavian ice sheet began to form on the territory of Fennoscandia. Its development to the maximum boundaries was accompanied by ice sheet advances or, on the contrary, strong retreats that reflected numerous successions of colder and warmer climate phases over a long period, called the Valdai (Weichselian, Vistulian) ice age. The Scandinavian ice sheet did not reach its maximum simultaneously at the different lobes. The age of the maximum boundary on the continent becomes younger from west to east, which is associated with the paleoclimatic setting in the northern part of Eurasia due to the formation of the extracontinental climate. The climate continentality increased eastward along the periphery of the ice sheet. These climate features and the ice sheet response determined the nature of glacial morphogenesis in the proglacial zone. The conditions for the formation of the peripheral ice sheet and the increase in the number of mudflows and the formation of proglacial lakes were more favorable during the ice sheet degradation than expansion. The forms of active and dead ice, especially the terminal moraines and kames of different types, the valleys of marginal meltwater channels, and outwash plains reflect the stages of warming and degradation of ice sheets .