Studies of the margin morphology of small fully dry-based glaciers of the McMurdo Sound area have been continued in the Terra Nova Bay, Cape Bird (Ross Island), and Dry Valleys areas. Normally, very limited amounts of debris are carried by these glaciers, but some glaciers in the Terra Nova Bay area are found to have large zones of debris-covered ice. Preliminary results indicate that this debris was originally left as a discontinuous sheet of ice-cored Ross Drift following retreat of the Pleistocene Ross Sea I advance of the Ross Ice Shelf. Holocene glacial expansion has formed glaciers by direct accumulation on to areas of ice-cored drift located in hollows. Glaciers thus formed have a till bed entrained by stratigraphy, flow on Pleistocene ice, and disgorge the sediment as a broad ice-cored “inner moraine”.
Outlet glaciers of the small Cape Bird ice cap superficially appear to have recently retreated back from large ice-cored moraines at their margins. A reconnaissance has shown that these glaciers are actively advancing and that the extensive debris output was derived from entrained ice-cored drift of the Ross Sea I glaciation which is being re-deposited.
In the Dry Valleys area, a number of glaciers enter enclosed lakes and here the contact between lake ice and glacier ice is permanent and cannot ablate. The lake ice must therefore move with the glacier. This configuration has the possibility of rafting glacial moraine across the lake before it is deposited. Multiple cases of different configurations are possible with either rising or falling lake levels and advancing or receding glaciers. Massive beds of regelation ice, where lake water has frozen on to the glacier sole, have been found at one glacier/lake junction.
