CORRELATION OF HOLSTEINIAN FLUVIAL SERIES IN POLAND AND BELARUS

Buried fluvial series of the Holsteinian Interglacial in Poland and Belarus have been correlated using palaeogeographical analysis based on records from numerous boreholes and biostratigraphically studied key sections. Stratigraphic position and palaeogeography were determined by correlation with Holsteinian marine sediments in the Kaliningrad District of Russia and the Late Elsterian glaciolacustrine series in the southern peribaltic region.

Studies of over a hundred interglacial sites from Belarus have revealed regional differences in distribution and composition of Holsteinian sediments. River series prevail in central and eastern part of the country, whereas Holsteinian deposits within the Neman drainage basin of western Belarus are mainly of lacustrine origin and fluvial sediments are scarce. In contrast, central Polish fluvial sections are pretty numerous and fluvial sediments are considerably thicker.

Geological setting of Holsteinian river deposits in mid-eastern Poland and western Belarus appears to be determined by location of the underlying glaciolacustrine sediments. In fact, the Holsteinian river system up-stream has been created in this area by erosion due to spilling of water from Elsterian glacial lakes. Conditions favouring extensive drainage towards the Holsteinian Sea existed in western Belarus and in Poland, whereas the river network of central and eastern part of Belarus was drained to the Black Sea basin.

In the adjacent areas of Poland and Belarus, the main interglacial watercourse was different from the modern one and the western direction of drainage prevailed. The main watershed between the Baltic and the Black Seas during the Middle Pleistocene was located westwards in comparison with its present position. However, the secondary watershed between the Central Poland rivers and those drained directly into the Baltic Sea has been only slightly modified since that time.