Central Asian glaciers, compared to other glaciers in the world, should exhibit a different response to changing climate owing to (i) the extreme continentality that gives rise to aridity and large seasonal temperature variations, and (ii) the coincidence of accumulation and ablation seasons in summer. A detailed 4year field survey has been carried out on Sofiyskiy glacier in the south Chuya range(Altai mountains), Russia. Field observations reveal that this glacier retreated steadily during the 20th century at a rate of 18.3 m a–1, considerably faster than Maliy Aktru glacier, 30km to the north. Based on radio-echo sounding (RES), the subglacial topography of Sofiyskiy glacier has been reconstructed, and stake and snow-pit measurements enable the determination of surface velocity and mass balance. Basal sliding plays an important role in Sofiyskiyglacier’s behaviour, as is shown by a force-balance analysis. An analysis of RES measurements yields the bed reflection power (BRP). Using the three-layer reflectivity model of Born and Wolf (1986), the BRP is compared with the theoretical bed reflectivity for two contrasting layers of varying porosity and thickness. Results indicate that Sofiyskiy glacier possibly exhibits a polythermal regime.
The soils of Russian Altai highlands were used as a paleoenvironmental archive, as a source of dating material, and as a chronostratigraphic marker to describe Holocene environmental change in the studied area. Based on calibration intervals of 14C dates obtained for buried humus horizons (11 buried soils in 6 studied soil-sedimentary sequences) and some dates from pendants of contemporary soils, following stages of pedogenesis were recorded in studied soil-sedimentary systems and surface soils: 6.4 – 11.5 ky cal BP; about 4.9-5.3 cal BP; 2.5-3.8 cal BP; 0.6 – 1.2 cal BP. All studied surface soils in the basins nowadays develop in cold, ultra-continental water deficit conditions: Skeletic Kastanozems Cambic, Skeletic Cambisols Protocalcic, Skeletic Cambic Calcisol Yermic. The most extreme conditions of soil formation within Holocene were within the last 1-2 kyr. All buried soils were formed in better conditions, more balanced in water, with higher biological activity, mostly within steppe or forest-steppe landscapes. Cryogenic features had been insisting all over the Holocene till nowadays. Water demandant cryogenic features are met in buried soils up to the age of 1-2 ky cal BP. In the last millennia cryogenic processes are suppressed, water demandant features gave way to those which can be formed in contemporary water deficit conditions: simple fissures, frost sorting, and shattering. At lower levels (Kuraj basin) more or less arid cold steppe conditions insisted within the most part of Holocene. Initial stages of soil formation were often ground water affected, or at least shortly waterlogged. At the highest positions humid and relatively warm Early Holocene stage of forest pedogenesis is recorded for the beginning of Holocene, and a Late Holocene (last 3-4 kyr) cold humid phase, presumably under mountain tundra and/or alpines. Microsedimentary intra-soil record in carbonatehumus pendants imprints fine fluctuations of soil water regime at initial stages of soil formation, controlled by local topography, and climatic changes in the second half of Holocene. General trends of environmental changes in the region recorded in soil and soil sedimentary systems are in well correspondence with other records of paleonvironment.
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