GLACIAL GEOMORPHOLOGY OF THE WILLIAMS AND SCHMIDT HILLS, PENSACOLA MOUNTAINS, ANTARCTICA

We mapped glacial geologic features in the Schmidt and Williams Hills, ranges of nunataks adjacent to Foundation Ice Stream (FIS). FIS, which flows past the western flanks of the Pensacola Mountains in West Antarctica, drains ice from the central EAIS into the WAIS, and discharges into the Weddell Sea Embayment. Our maps allow us to identify past changes in ice thickness, which improve our understanding of ice sheet response to climate change. Glacial erratics with distinct extents of weathering reveal at least two periods of glaciation. Evidence indicates that during a glacial maximum local ice thickness exceeded current ice thickness by 700 m, and was thick enough to flow obliquely over the hills, toward FIS. During subsequent deglaciation, ice flow became topographically constrained and only ice-stream-parallel flow is recorded. In addition, the preservation of erratics perched on patterned ground and frost-shattered bedrock represent at least two glaciations, and suggest the presence of thin, cold-based ice cover. This interpretation is supported by sparse evidence of glacial erosion. Future work will use surface-exposure dating to determine the timing of glacial advance and retreat.