ИСТИНА

Numerous uplands last glaciated by the MIS-6 ice cover are of the major landscape elements of Central European Russia. Usually arranged as large ridges with series of end moraines they also are represented by smaller isolated heights with widespread glaciolacustrine deposits and well-preserved kame and kettle topography. Both types are covered by pronounced yet differentiated thickness of mantle loams. Those landscapes are commonly referred to as being relatively stable ever since the last glaciation (Moscow or Late Saalian) except for intensified erosional incisions during transition periods from late glacial stages to interstadials or interglacials. However, thoroughly investigating postglacial cover of watershed landscapes at the Borisoglebsk Upland we revealed major shifts in a set of geomorphic agents and its dynamics that have substantially shaped the exterior of such uplands during the entire Late Pleistocene and Holocene. The key site is situated near the City of Rostov the Great. The northeastern macroslope of the Borisoglebsk Upland has a step-rolling landscape structure descending from over 210 m down to the Nero Lake level at 93 m a.s.l. Low geomorphic connectivity is caused by a series of leveled surfaces partially inherited from the initial depressions of glacial origin, but significantly smoothed by the Late Pleistocene sedimentation. Up to 8-15 m of postglacial loamy and silty thickness with distinct lamination of several orders often fill in those depressions being facially substituted by less prominently stratified deposits on the surrounding footslopes. Those well-laminated silts and loams with several organic-rich layers are believed to be lacustrine sediments of shallow local Late Pleistocene lakes yet broadly spread through the studied area. Sediment input from adjacent slopes was of the major controls for such infillings and due to specific lenticular structure and subangular silty inclusions is well recognized in cores and sections. A set of radiocarbon dates, pollen reconstructions, results of lithological and palepedological analyses and correlation with the previously published data suggest that prolonged lacustrine sedimentation and several intensifications of slope mass movement have significantly lowered relative elevations within glacial watersheds. Penetrated by a sequence of cryogenic relict units and incorporating a series of paleopedogenic features, that stratum displays a potential to be a reliable archive for the detailed paleogeographic reconstructions and an important link between long-studied fluvial network history of the region and yet to be deciphered watershed proxies of the uplands.