Middle and Late Quaternary glacial lake-outburst floods, drainage diversions and reorganization of fluvial systems in northwestern Eurasia

Abstract

The Middle and Late Pleistocene glaciations of northern Eurasia had a great impact on the evolution of the modern drainage system. This paper presents a review and synthesis on the palaeogeography of glacial lakes, their drainage and impact on the re-organization of the drainage systems during the last two glacial-interglacial cycles. We will focus on four regions: (1) northern Central Europe and Fennoscandia, (2) the central part of the East European Plain, (3) the west Siberian Plain and (4) the Aral – Caspian – Black Sea area. The main findings of the last decade(s) include the improved chronology of some major river system formation and of meltwater overflows across the continental drainage divides. Major drainage systems of the north-central and west-central part of the East European Plain (upper Volga, upper Dnieper) formed due to overspill of glacial lakes in late MIS 6 with a partial re-organization (upper Dnieper) in MIS 2. The Aral – Caspian – Black Sea cascade acted as a sink for glacial meltwater from the north. The major meltwater yield to the Aral and Caspian seas occurred in MIS 6 and late MIS 5. In MIS 2, the meltwater delivery via the Volga valley into the Caspian Sea was low and therefore had only a minor influence on the sea level. Considerable meltwater discharge to the Black Sea through the Dnieper River system occurred around the maximal stage of the MIS 2 glaciation and ceased very quickly after the onset of deglaciation.