On the existence of a large proglacial lake in the Rostov‐Kostroma lowland, north‐central European Russia

The Rostov-Kostroma lowland is a depression stretched between the end-moraine ridges of the Moscovian (MIS 6) glaciation crossed by the Upper Volga River. According to the theory accepted since the 1970s, in the Last Glacial epoch (MIS 2) this lowland was occupied by a glacially dammed lake that drained about 15 000 years ago, allowing the modern river system of the Upper Volga to appear. In this study, we test this concept using a synthesis of previously published data and new data on geomorphology, structure and age of the Late Quaternary deposits. The results obtained show that the last large lakes existed in this area during deglaciation at the end of MIS 6. By the beginning of the Last Interglacial (MIS 5e), these lakes were drained, and the present-day Volga valley already existed. Small lakes remained in the deepest glaciodepressions, with few of them surviving until today. These lakes show no signs of depth or area increase in MIS 2. Lacustrine deposits of MIS 2 have not been found elsewhere. Therefore, no evidence of a single large lake in the Rostov-Kostroma lowland in MIS 2 was found. The total area of the lakes did not differ much from that of modern times.