Multiple Early to Mid-Pleistocene East Antarctic Ice Sheet variations in the Ricker Hills (Victoria Land, Antarctica).

Timing and amplitude of Antarctic ice level changes as response to past climate fluctuations are a major issue in paleoclimatology. In this study, we determined surface exposure ages with in situ produced cosmogenic nuclides (10Be, 21Ne) of four erratic boulders from a pre-last glacial deposit in the Ricker Hills, southern Victoria Land, located at the boundary of the East Antarctic Ice Sheet. The investigated area is not affected by alpine glaciers. Thus its glacial features and deposits are a direct proof of past ice sheet variations. Consistent neon and beryllium exposure ages indicate two major ice advances, one at about 1.4 Ma and another one around 1.0 Ma before present. Evidence for a third glacial event comes from an erratic boulder that was intermittently buried by cold-based ice. From our data we infer an upper age limit for this third event at around 665 ka.