干旱区生态环境知识资源中心

Paleoenvironmental conditions are reconstructed from soils buried under volcanic ash ca. 21,500 years ago on the Seward Peninsula. Soil development was minimal, reflecting the continuous regional deposition of loess, which originated from river floodplains and the exposed Chukchi shelf. Cryoturbated soil horizons, ice wedges, and ice-lens formation indicate a permafrost environment and mean annual temperatures below -6 degrees to -8 degrees C. Shallow active layers (average 45 cm), minimal evidence for chemical leaching of soils, and the presence of earthen hummocks indicate a cold and seasonally dry climate. Neither steppe nor polar desert soils are appropriate analogues for these zonal soils of loess-covered central Beringia, No exact analogues are known; however, soils underlying dry tundra near the arctic coast of northern Yakutia, Russia, and under moist, nonacidic tundra of the Alaskan North Slope have properties in common with the buried soils. (C) 2000 University of Washington.