O ilości górnoplejstoceńskich zlodowaceń w północno-zachodniej części Równiny Rosyjskiej

Abstract

NUMBER OF UPPER PLEISTOCENE GLACIATIONS IN THE NORTH-WESTERN PART OF THE RUSSIAN PLAIN

Summary

As concerns the Quaternary geology of the Russian plain, the stratigraphic subdivision of the Upper Pleistocene has so far been one of the questions discussible. Differences in opinions concern mainly the number of the glaciations younger than the Mikulino Interglacial. There are some opinions that at least one glaciation of this kind existed, i.e. Valdai Glaciation. Other scientists suppose that two such glaciations existed, separated by the Mologo-Sheksna Interglacial (A. I. Moskvitin, 1947; W. P. Gritshuk, 1961). Another group of scientists, among others N. I. Apukhtin, I. M. Pokrowskaja (1960), is of the opinion that the Mikulino Interglacial was followed by these glaciations.
To explain this problem multilateral detailed studies were made on the section at Rybinsk, representative to distinguish the Mologo-Sheksna Interglacial. The spore-and-pollen diagrams, elaborated once more, revealed the development of vegetation typical of the Mikulino Interglacial. The repeated dating by C¹⁴ method (Table 1) demonstrated that these deposits are older than it could have resulted from previous datings.
The section from Balzana, thought by W. P. Gritshuk to be a stratotype of the Mologo-Sheksna Interglacial, proved to be of Holocene age. Respective dates were published by N. S. Czebotarieva, E. A. Malgina (1965).
As proved by the recent studies, the deposits thought by N. I. Apukhtin to belong to the Mga Interglacial, can be referred to the Mikulino Interglacial.
Thus, no deposits are known at present to occur within the Russian Plain area, which might prove the presence of an interglacial younger than the Mikulino Interglacial.