Grain Size Composition of Neopleistocene Basal Moraines in the Northeasternmost Area of the Russian Plain

Generalization of the grain size analyses of the basal Neopleistocene moraines from the sections of coastal outcrops and boreholes in the vast European Subarctic region of Russia and in more southern areas of the Timan–Pechora–Vychegda region showed that the moraines are typical mixed, almost unsorted rocks with similar contents of the gravel–sand, silt, and clay fractions, serving as one of the arguments in favor of their glacial genesis. Their grain size composition is related to the peculiarities of rocks in the glacier bed. It is formed during the crushing, abrasion, and mixing of the glacier-rafted, assimilated, and transported material during its transportation and deposition, which determines variability of the grain size composition of moraines. Consequently, the grain size composition of moraines in combination with other lithological data reflects the pathway and dynamics of the glacier movement.