The Upper Don River valley evolution in the end of the Late Pleistocene

The relicts of large palaeochannels (macromeanders) are widespread on the floodplains in river valleys of the Don River basin. These macromeanders indicate river runoff several times above the modern one. Such macromeanders were found in the Upper Don River valley. To reconstruct the Late Pleistocene evolution of river valleys the study near Epifan town was organized. It included mechanical coring and radiocarbon and OSL dating of alluvium. Basing on the data we reconstructed the main stages of the Don River valley evolution in the end of the Late Pleistocene and identified the epochs of high runoff and macromeanders formation and the intermediate epochs of low runoff and accumulation in the valley. The river incision below the present-day level due to climate changes and higher river runoff dated back to about 30-35 ka BP. During the LGM time (20-23 ka BP) the river runoff decreased as a result of climate aridization and the incision gave way to accumulation in the river valley. After the LGM the high runoff epoch started, dating about 13-19 ka BP. During that time large meandering palaeochannels (macromeanders) formed a wide valley bottom. Two periods of their development, about 17-19 ka BP and 13-15 ka BP, were separated by a low runoff period (~16—15 ka BP). During the Holocene the river runoff was lower than in the Late Pleistocene.

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