ICE LAKE VALLEY GLACIATION, HÖH SERH RANGE, MONGOLIAN ALTAI

By Andrea Seymour

Whitman College, Walla Walla WA

Abstract:

            The Mongolian Altai preserves a glacial record since the late Pleistocene. Small glaciers still exist in the tectonically active Höh Serh Range. Ice Lake Valley in the center of the range contains moraines and granitic erratics that indicate past ice limits and Equilibrium Line Altitudes (ELAs) in the currently non-glaciated valley. Samples of granitic boulders were collected for cosmogenic 10Be dating to determine when three moraines were deposited. The moraines are predicted to be Last Glacial Maximum (LGM) and younger. The dating results for the oldest moraine, the terminal moraine, show that it was deposited at 37 ka. Using the Toe-to-Summit Altitude Method and an Accumulation Area Ratio of 67%, ELAs at the oldest to youngest three times of climate stability were 3065 m, 3200 m, and 3240 m. Today the snowline is believed to be above 4000 m. Based on a normal lapse rate of 1.98°C/300m, the temperature rose more than 6.2°C from the LGM to today. This change in climate affects the snow pack and the water supply on which the nomads of the area depend.