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Ice-marginal depositional processes in a polar maritime environment, Vestfold Hills, Antarctica.

S.J. Fitzsimons

 
Abstract

This study investigates the processes of ice-marginal sedimentation in Vestfold Hills, Antarctica. Most debris is released from the ice when basal and englacial debris bands become warped and reach the surface of the glacier and where the debris bands are exposed by ablation of the ice surface. Once released, the debris is redistributed in the ice-marginal area by depositional processes that are controlled by the availability of water. During the short summer, melt water from snow and ice saturates the newly released debris and causes sediment flows and other mass-movement deposits. Melt-out and sublimation tills form after the layer of debris on the moraines is consolidated and melting rates decrease. When the thickness of deposits on the surface of ice-cored moraines reaches or exceeds the depth of summer thawing, the ice core no longer melts and the moraines become semi-permanent features. The sediments and land forms of the ice-marginal area closely resemble those formed by sub-polar glaciers with a complex thermal regime and are unlike those that form at the margins of dry-based polar glaciers. Although glacier thermal regime is understood to be a major control on debris dispersal and processes of glacial sedimentation, the evidence from Vestfold Hills suggests that the primary control is the climate of the glacier terminus area.

Key Words Plus: CORED MORAINE; TILL; GLACIER; PINGOS

 
Reference

Fitzsimons, S.J. 1990. Ice-marginal depositional processes in a polar maritime environment, Vestfold Hills, Antarctica. Journal of Glaciology 36 (124), 279-286.

 

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