Soils and late Cenozoic history of the upper Wright Valley area, Antarctica

Abstract

Within the small alpine valleys at the western end of the Asgard Range, between the Wright and Taylor Valleys, moraines are found which appear to be older than those previously described in the Wright and Taylor Valleys. These moraines have been placed in order of relative age by the weathering and amount of profile development in the soils found on them. The alpine valleys may have formed during the initial glaciation of Antarctica when the major glacial features of the topography were formed. Within these valleys there is evidence for at least two periods of glacial erosion and moraine formation, during which the Wright Valley was completely filled with ice. These episodes must therefore be older than the Wright Upper IV episode which occurred more than 3·7 million years ago Because of their isolation and lack of precipitation, the valleys have been little affected by subsequent glacial events, and the alpine glaciations recorded elsewhere in the Wright Valley have left only small deposits around snow-drift fed ice tongues. The glacial history of Antarctica between the full bodied stage of glaciation in mid-Miocene times and the late Pliocene Wright IV episode must have been quite complex. Traces of glacial events during this period may also be found in other localities high above present ice levels.