Dynamics of the late Pleistocene Big Timber glacier, Crazy Mountains, Montana, USA

Abstract

The late Pleistocene Big Timber glacier of west-central Montana was used as the test case for a model which calculates the mass balance of a paleoglacier using glacial flow theory. Application of Glen's flow law to a detailed reconstruction of the glacier provided an estimate of the component of mass flux due to internal deformation. Assuming basal slip to be zero where mass flux at the equilibrium-line altitude (ELA), an ablation gradient of 3.0 mm/m. and an accumulation gradient of 1.0 mm/m were determined. The low gradients indicate that, during the last glacial maximum, the east side of the central Rocky Mountains experienced a cold, dry environment much like that of modern-day glaciers in the Brooks Range of Alaska. -from Authors