Late Pleistocene glacial chronologies and paleoclimate in the northern Rocky Mountains

• DOI: 10.5194/cp-18-293-2022
• Publication Date: 2022-02-15T08:14:14Z
• Authors: Brendon J. Quirk; Elizabeth Huss; Benjamin J. C. La...; Eric Leonard; Joseph Licciardi; Mitchell A. Plummer; Marc W. Caffee
• Keywords: Paleoclimatology; Deglaciation; Surface exposure dating; Last Glacial Maximum

Abstract. The geologic record of mountain glaciations is a robust indicator terrestrial paleoclimate change. During the last glaciation, ranges across western US hosted glaciers while Cordilleran and Laurentide ice sheets flowed to west east continental divide, respectively. Records detailing chronologies significance these advances have been developed for many sites North America. However, relatively few glacial records in northern Rocky Mountains near former sheet margins. Here, we report cosmogenic beryllium-10 surface exposure ages numerical glacier modeling results, which show that Rockies abandoned terminal moraines after end global Last Glacial Maximum around 17–18 ka could sustained by −10 −8.5 ∘C temperature depressions relative modern assuming similar or less than precipitation. Additionally, present deglacial chronology from indicates there considerable variability initial moraine abandonment Mountains, pace subsequent retreat through late exhibits some regional coherence. Our results provide insight on potential mechanisms driving initiation deglaciation US, including rising atmospheric CO2 collapse.