CONSTRAINTS TO THE AMPLITUDE OF PLEISTOCENE ICE LEVEL VARIATIONS IN THE TRANSANTARCTIC MOUNTAINS FROM GLACIAL GEOMORPHOLOGIC MAPPING AND SURFACE EXPOSURE DATING

Did the volume of the Antarctic ice cover fluctuate synchronously to the past climate changes that occurred in the northern hemisphere? Or have the southern ice sheets remained unaffected by these partly abrupt warming and cooling events? The glacial deposits at the margin of the East Antarctic Ice Sheet (EAIS) reflect volume changes of the inland ice in the past. We have mapped glacial landforms on nunataks and in other ice-free areas along the Transantarctic Mountains within an project ongoing since 1996. The result is a series of 1:250,000 scale geomorphological and glaciological maps showing in detail the distribution of glacier and sea ice features, glacial, periglacial, aeolian and weathering landforms and deposits. At least five glacial drifts at different elevations have been differentiated and correlated over large areas. In addition, we have dated erosional and depositional glacial features at selected sites by surface exposure dating with in-situ produced cosmogenic He-3 and Ne-21. At the Ricker Hills, situated 100 km inland west from the Ross Sea coast, we obtain new exposure ages ranging between 160 and 680 ka. The combination of mapping and dating allows the conclusion that the EAIS did undergo surface level changes throughout the Pleistocene, but that these have been of limited amplitude, up to 500 m on Ricker Hills. This agrees with findings from further north in Northern Victoria Land. More datings from the same and other sites are in progress.