RECONSTRUCTION OF PLEISTOCENE GLACIERS AND CLIMATE IN THE BAKER CREEK VALLEY, GREAT BASIN NATIONAL PARK, U.S.A

During the last Pleistocene glaciation, the South Snake Range in Great Basin National Park hosted at least seven valley glaciers. The largest valley glacier occupied Baker Creek valley. A suite of terminal moraines and other glacial landforms in the valley clearly mark the extent of the past glacier. Reconstructing the magnitude of Pleistocene climate change in this sector of the Great Basin can help to better understand the relative roles of temperature and precipitation in driving glacier expansion. A numerical model of glacial mass balance and ice flow was applied to Baker Creek valley to identify a range of possible temperature and precipitation combinations accompanying the last glaciation. The model uses calculations of monthly snow and energy balance based on meteorological data to compute a net mass balance of a glacial valley. The net mass balance is input as a distributed source to term to an ice flow model that simulates ice extent and thickness. Temperature and precipitation values are adjusted from modern to produce a mass balance that yields the known ice extent. Model results include a broad range of possible temperature and precipitation combinations indicating that if precipitation was similar to modern during the last glaciation, then a temperature depression of 8.8°C accompanied the time of maximum extent. This result is similar to findings based on the same glacier modeling methods in the Ruby and East Humboldt Mountains in the northern Great Basin and the Wasatch Mountains in the northeastern Great Basin, suggesting a uniform regional temperature depression during the last glaciation.