PALEOGEOGRAPHIC RECONSTRUCTIONS OF PONTIC LOWLAND AND NORTHWESTERN BLACK SEA SHELF FOR THE PAST 25 KY

Geological mapping (1:200,000 and 1:50,000 scale) and analysis of sedimentary environments on the northwestern Black Sea shelf, were used for paleogeographic reconstructions for the time periods of 25 ka, 18 ka, 12 ka, 9 ka and 6 ka BP. The landscape of 25 ka BP, when sea level was 87 m below present, consisted of three geomorphic elements: 1) denudation plain incised by numerous rivers and uniformly dipping southward from 180 to 80 m; 2) Late Pleistocene alluvial terrace plain, within which the valleys of Dnieper, Dniester and Danube formed a common alluvial plain segmented by local drainage divides, and 3) low coastal delta plain that represented a zone of intense fluvial deposition, which is presently located on the outer shelf. The subsequent sea-level rise of the Neoeuxinian sea-lake to -55 m (18 ka BP) and -37 m (12 ka BP) resulted in the flooding of deltaic lowlands and a large portion of the alluvial terrace plain containing deeply embayed Dniester and Dnieper limans. The estuary that formed in the flooded Danube valley bordered this plain on the southwest. As a result of the next transgressive phase 9 ka BP, the sea flooded almost the entire Late Pleistocene alluvial terrace plain, with Dniester and Dnieper limans converted to open marine embayments. During Kalamitian time (6 ka BP), the entire Chilia section of the Danube delta was flooded, while the modern Dniester shoal still contained promontories and possibly small islands. A large tract of land existed in the region of Tendra Spit and modern Odessa Bank. During 25 ka BP, forest and steppe landscapes covered drainage divides along the denudation plain, with forests common for the highlands and valley slopes of rivers and gulleys. The steppe zone occupied the alluvial plain, which dominated the landscape to the south. The soil profile contained more than 20 soil types. Later, the drainage divides consisting of loess still preserved subaerial steppe and forest-steppe landscapes, whereas riparian communities developed on alluvial sands and muds along river valleys undergoing active sedimentation. Our study demonstrates that paleogeographic reconstructions may serve as a basis for locating submerged ancient settlements, as well as for constraining the likely population migration routes.