PALEOGEOGRAPHIC СONDITIONS OF DNIPRO AGE AND THEIR ROLE IN THE FORMATION OF LITHOGENIC BASIS OF THE LANDSCAPES OF THE TERRITORY OF SUMY REGION

Abstract

The Dnipro ice age is one of the colds paleoclimatic epochs of the Pleistocene, which is characterized by the wide development of ice sheets and covered a period of about 50 thousand years (from 180 to 127 thousand years ago). The purpose of this article is to establish, through the associated use of chorological and historical approaches, the role of the Dnipro glaciation in the landscape genesis of the region. Analysis of boreholes of hydrogeological exploration, studies of outcrops in quarries, cliffs of river bedrocks and deep ravines made it possible to establish a two-membered structure of the Dnieper stratolithological complex in the region: the lower (more ancient bottom-erosion) horizon of boulder deposits, represented by brownish or gray clay with the inclusion of Fennoscandinavian erratic big and small boulders, as well as fragments of local bedrock – sandstones. The upper junior horizon is formed by heavy boulder loam of yellowish-brown or reddish-brown color. This ablative moraine also contains many boulders, pebbles and even huge boulders up to 3 m in diameter (today they are very rare in wooded areas, since the vast majority of it have long been removed by the local population for housekeeping and household needs). In the periglacial (boundary non-glacial) zone, where severe climatic conditions existed during the glaciation, with the formation of permafrost or thick seasonal permafrost and rather sparse biota, peculiar lithomorphosystems were formed and specific cryosolifluction morphogenetic processes were occurred. The latter were consisted in a significant gravitational removal of loose slope material (cryodeluvium) and filling by it of glacial fluviogenic morphosystems: river valleys, gullies and ravines. As a result, local interfluve plateaus, terraced and bedrock slopes of river valleys were leveled, their exogenous asymmetry and valley pediments were formed.