GLACIAL AND PERIGLACIAL DEPOSITS OF THE TUMBLEDOWN-CLIFFS AREA, JAMES-ROSS-ISLAND, WEST ANTARCTICA

Investigations of the glacial geology of an ice-free area between loca l glaciers on western James Ross Island have shown that recent glaciat ion consists of small cirque glaciers and outlet glaciers from the cen tral icefields. Erratics are evidence of an earlier, more widespread g laciation. Two till types are found in the area, a thin, erratic-beari ng older diamicton interpreted as a lodgement till or a glaciotectonit e and a younger, local till of supraglacial origin forming the recent terminal moraines. The present grounding line lies close to the sea le vel, resulting in subglacial deposition. A former more extended glacie r was grounded further out in the Prins Gustav Channel. Frost action i s intense in the cold, continental climate and large volumes of talus are produced. Rock glaciers are common, probably of both talus and gla cier derived origin. The glacial and periglacial features, including a kame terrace and a raised beach, imply that the area has been ice-fre e throughout the Holocene and possibly longer.