Archaeological Sites as Markers of Neopleistocene-Holocene Hydrological System Transformation in the Kurai and Chuya Basins, Southeastern Altai: Results of Geomorphological and Geoarchaeological Studies

Abstract

Multidisciplinary studies using geomorphological, geoarchaeological, and geochronological approaches indicate contrasting environmental changes in Southeastern Altai, beginning in the Late Pleistocene. 29 new radiocarbon dates from the subaerial complex overlying Late Neopleistocene sediments in the high-altitude Kurai and Chuya basins confi rm the degradation of a single ice-dammed reservoir in that area before the Early Holocene. In the fi rst half of the Holocene, those basins were fi lled with isolated lakes. At the mouth of the Baratal River in the western Kurai basin, a reservoir with a water-level of at least 1480 m a.s.l. emerged ca 10–6.5 ka cal BP; whereas in the Chuya depression, numerous residual lakes existed at least 8 ka cal BP. Landslide- and moraine-dammed lakes between the depressions in the Chuya River valley existed until 7–3 ka cal BP, when they drained away. The state of preservation of in situ archaeological sites, their cultural affi liation, and their locations within the depressions and along the main Chuya valley attest to spatial and temporal changes in the hydrological system. This evolution in the second half of the Holocene did not entail major consequences for humans. All cataclysmic fl ood events took place (occurred) before 10–8 ka cal BP.