Depositional landforms and sediments in western Vestfold Hills, East Antarctica

Areas around western Vestfold Hills, East Antarctica, feature two sedimentary units in outcrops and excavations. Uppermost Dingle Sand is a gravelly, silty sand with boulders, which drapes bedrock ridges and more thickly covers valley floors and continues below modern sea level. Underlying Vestfold Beds are gravelly, muddy sands that are found in deeper valley fills. High-resolution aerial photography, topographic and bathymetric surveys, sediment grain size and field observations indicate that Dingle Sand formed as ablation till during the last deglaciation. Post-depositional modifications of Dingle Sand by decay of ground ice, mass movement, water, wind and marine transgression and regression have altered the texture, structure and fossil content in this region. Vestfold Beds are older, finer-grained tills. Indirect age estimation of Dingle Sand suggests deglaciation-age deposition with younger (Holocene) reworking in places, whereas Vestfold Beds may be as old as the Pliocene. These sediments post-date the early Pliocene Sørsdal Formation found on Marine Plain in southern Vestfold Hills. Identification of Dingle Sand as a separate, primarily glacial deposit helps clarify the glacial history of the Vestfold Hills. Evidence for marine modification of the deposits after deglaciation suggests that other regions might also have glacial deposits interpreted as marine because of post-depositional processes.