Last Glacial Maximum equilibrium-line altitude trends and precipitation patterns in the Sangre de Cristo Mountains, southern Colorado, USA |
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| Authors: | KURT A REFSNIDER KEITH A BRUGGER ERIC M LEONARD JAMES P McCALPIN PHILIP P ARMSTRONG |
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| Institution: | Institute of Arctic and Alpine Research and Department of Geological Sciences, University of Colorado at Boulder, 1560 30th Street 450 UCB, Boulder, CO 80303, USA;;Geology Discipline, University of Minnesota at Morris, Morris, MN 56267, USA;;Department of Geology, Colorado College, 14 E. Cache La Poudre, Colorado Springs, CO 80903, USA;;GEO-HAZ Consulting, Inc., 600 E. Galena Avenue, P.O. Box 837, Crestone, CO 81131, USA |
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| Abstract: | Precipitation patterns during the Last Glacial Maximum (LGM) in the Rocky Mountains varied due to the influence of the continental ice sheets and pluvial lakes. However, no constraints have been placed on potential changes of southeasterly Gulf of Mexico-derived moisture that today contributes considerable precipitation to the easternmost ranges of the southern and middle Rocky Mountains. The Sangre de Cristo Mountains of southern Colorado are ideally situated to assess the relative importance of westerly and southeasterly-derived moisture during the LGM. Based on reconstructions of 30 palaeoglaciers in the Sangre de Cristo Mountains, we find that LGM equilibrium-line altitudes (ELAs) on the east side of the range were systematically 100–200 m lower than ELAs on the west side. The observed ELA pattern is strikingly similar to modern precipitation patterns in the study area, suggesting that southeasterly-derived precipitation had a significant influence on the mass balances of LGM glaciers. |
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