NUMERICAL MODELING OF LATEST PLEISTOCENE GLACIER MASS BALANCE AND ICE FLOW IN BAKER CREEK, GREAT BASIN NATIONAL PARK, NEVADA

The Baker Creek valley in Great Basin National Park, Nevada exhibits one of the most pristinely preserved terminal and recessional moraines of the last Pleistocene glaciation and hosts the only perennial ice in Nevada in its high-elevation headwaters. Along with the geomorphology of the head of Baker Creek valley, the moraine sequence was used to reconstruct the maximum and recessional extents of the largest Pleistocene glacier in the park, which provide clues to temporal changes in climate during the last glacial-interglacial transition. A physically based, 2-D numerical model of steady state glacier mass balance and ice flow was applied to the Baker Creek valley to simulate ice extents during the last glaciation and deglaciation. Model parameters were calibrated using the modern distribution of perennial snow and ice above the Wheeler Peak Rock Glacier. Model simulations of maximum and recessional ice extents yield the range of temperature and precipitation combinations that could have accompanied intervals of moraine deposition, assuming that the glacier was at steady state. Results of model experiments indicate that if precipitation was near modern, then a temperature depression of 9°C accompanied the interval of maximum ice extent. This finding is consistent with the results yielded by applications of the same modeling method to glacial valleys in northeastern Nevada, all of which indicate a temperature depression of 9° to 10°C during the last glaciation assuming modern precipitation. The magnitude of this temperature depression is consistent with those predicted by recent paleoclimate models for latitude N39° but is slightly greater than temperature depressions inferred for similar latitudes in California and Colorado.