This research project will complete current U.S. Argentine research in Patagonia and expand to include related research in Tierra del Fuego. Mapping of the oldest surficial drift deposits will be completed in Patagonia. The new research in Tierra del Fuego includes mapping, dating and correlating pre-to-late glacial and raised shorelines between Rio Gallegos and Rio San Pablo using K-Ar and Amino Acid Racemization dating methods. The area contains a large region of "questionable glaciation" to be studied because of its importance as a potential refuge during glacial times. The investigation of raised shorelines will provide important information on the isostatic and neotectonic history of Tierra del Fuego. The investigators are rapidly developing an absolute, age controlled glacial history for this area which strongly supports the work of Mercer and his co-workers (1976, 1983). The Southern Andes represent the ideal locality to reconstruct the timing and magnitude of past glacial and climatic fluctuations.