Glaciations in the East European region of the USSR

Abstract

LOWER PLEISTOCENE Frenzel (1967) reconstructed the extent of this ice-sheet which represents, perhaps, one of the oldest glaciations in eastern Europe. This period was probably contemporaneous with severe cooling inferred from the finds of marsh lemmings Synaptomus in the Western Urals, from the Akchagyl layers (Sukhov, 1977) and one of the Akchagyl cooling episodes in the Volga area and North Caucasus established from paleobotanical and faunal records. In general, the Eopleistocene (1.2 to 0.7 Ma) involved several periods of cool climate. In the northwestern Plain, in the Baltic region (Lithuania) pollen spectra from the Daumantai suite suggests three phases of cooling with birch and pine forests and minor components of spruce and alder, succeeded by a warmer environment with dominantly mixed forests incorporating elements of Turgai flora (Vaitekunas and Khomutova, 1975). The classification and stratigraphical range and these variations is still under discussion. In Byelorussia, in the Brest layers which are equivalent to those of the Apsheron, a change of rhythms is shown by the alternation of tundra-steppe, steppe and forest associations (Makhnach, 1977). Judging from paleomagnetic data in the Don basin, the last cold stage of the Eopleistocene was colder than previous ones. It includes a typical loess formation and erratic boulders (brought by Eopleistocene glaciers?). The boulders occur in fluvial deposits in the Klepki section at the Osered river (Don drainage basin) under the unit with the Tiraspol fauna; they are thus ascribed to the Matuyama Polarity Epoch (Udartsev, 1980). In the southern Russian Plain three cold stages have . been identified from freshwater mollusks (Domashkino, Zhevakhov, and Morozov stages) (Chepalyga, 1980; Gerasimov et al., 1980). Yet no glacial deposits have been discovered whose Eopleistocene age could be demonstrated. Warm phases are indicated by red soil complexes (Table 1, Fig. 1). UPPER PLIOCENE OR EOPLEISTOCENE Glaciation in East Europe was influenced by geomorphological and climatic factors. The elevated ranges along the northern margin of the region in Scandinavia, Novaya Zemlya and North and Polar Urals, provided zones of accumulation for snow and Ice. Eastern Europe is among the regions where the concept of Scandinavian glaciation was based (Kropotkin, 1876). On the maps prepared by Nikitin (1885) the limit of Quaternary glaciation passed through the southernmost Russian Plain, downstream from the Dnieper, Don and Volga. The concept of multiple glaciation was pioneered by A.P. Pavlov (1925) and further developed by Mirchink (1928), Yakovlev (1932, 1956) and the fundamental work of Gerasimov and Markov (1939). From these major contributions evolved the concept of three principal glacial events in Eastern Europe: aka, Dnieper, and Valdai, which were correlated with the Mindel, Riss and Wiirm glaciations of Western Europe. Further research led to detailed subdivision of the glacial stages and definition of additional cold and temperate events.