Geological and Environmental Contextsof Pleistocene Occupation of the upper Yana River Basin, Northern Yakutia
Recent Quaternary palaeoecology and geoarchaeology investigations in the upper Yana River basin, the Verkhoyansk District, in the northern Yakutia have delivered new evidence on a regional palaeogeographical development, geological contexts as well as cultural manifestations linked to early prehistoric occupation of this marginal geographical territory. Alluvial formations and associated geomorphology forms (fluvial accumulation terraces built up of cobble gravels blanketed by fine-grain alluvial sediments occasionally inter-bedded by peat horizons) illustrate meandering stream settings and fluvial dynamics of laterally shifting riverine channels with relatively low geological base erosion. Sets of diagnostic core-and-flake industries made on selected fluvial clastic raw materials (quartz-quartzite-carbonate rock) from presently exposed and formerly buried alluvia along the active river banks in the Bytantay River valley (a left tributary of Yana) provide first indices on a pre-Holocene peopling of this subarctic Siberian region. Mapped sequences of organic and anorganic (silty-slay) strata within active permafrost geoenvironmental contexts document most detailed, high-resolution (palaeo)climate variations in the Yana Basin during the Final Pleistocene-Holocene time period. Well-preserved and taxonomically rich fossil fauna records found scattered on gravelly river banks and sealed in the intact geological positions in the Pleistocene colluvial formations 10-20 m above the present river point to a very high biotic potential of the last glacial (MIS 3-2) northern (forest-)tundra. Humanly modified large fauna bones (of horse, mammoth, rhinoceros and bison) show a co-existence of humans and fauna in the ice-Age ecosystems. The S-N oriented Yana River valley is considered as a most strategic corridor for early human expansion from southern Siberia into the Arctic territories.