Paleoclimatic Implications of the Relationship between Modern Snowpack and Late Pleistocene Equilibrium-Line Altitudes in the Mountains of the Great Basin, Western U.S.A.

Abstract

The variation of modern April-first water equivalent of the snowpack at the late Pleistocene equilibrium-line altitude (ELA) across the Great Basin is analyzed as a method of evaluating relative changes in late Pleistocene climates. Modern snow-course records were used to establish vertical April-first water-equivalent gradients for 24 mountain ranges in and near the Great Basin. These gradients were used to extrapolate the April-first water equivalent at the late Pleistocene ELA for 22 of the mountain ranges. Late Pleistocene ELAs were determined from the altitudes of lowest cirque floors and were taken from the literature. The results show a small increase in paleo-ELA with a large increase in water equivalent in the mountain ranges across the northern Great Basin. This suggests either that late Pleistocene temperature changes were not uniform across the northern Great Basin or that late Pleistocene snow accumulation patterns differed from those of the present or a combination of both.