New evidence of the total glaciation of the Isla Grande de Tierra Del Fuego

The stratigraphy and preliminary interpretation of a new locality with glac ial deposits in a previously interpreted ice-free area in Tierra del Fuego are presented. These deposits consist of basal proglacial gravels (at least 4-5 m thick) covered by the Drift Cabo Campo del Medio. The drift consists of a lower, 2 m thick, lodgment till and a upper, 7 m thick, glaciotectoni zed composite till, reflecting basal glacier shearing and upthrusting of gl aciofluvial deposits and lodgment till, with superimposed deformation by ge lifluction. These two main drift packages are interpreted as ground moraine s, reflecting two corresponding glacial advances with an intervening recess of the glacier front. The altitude of the Drift Campo del Medio, well abov e younger fluvioglacial deposits related to the Last Glaciation, the degree of erosional modifications, and its external position, to the NE of the La st Glaciation moraine system, are evidence suggesting that the Drift Cabo C ampo del Medio was related to a glaciation older than the Penultimate Glaci ation. The finding of this locality sheds new light on the old controversy of total vs partial ice coverage of the island. (C) 1999 Published by Elsev ier Science Ltd. All rights reserved.