Stratigraphic analyses of outcrops, shorelines, and diatoms from the southern Bolivian Altiplano (Uyuni-Coipasa basin) reveal two major lacustrine phases during the late-glacial period and the early Holocene, based on a chronology established by radiocarbon and U/Th control. A comparison of14C and230Th/234U ages shows that during times of high lake level, radiocarbon ages are valid. However, during low-water periods,14C ages must be corrected for a reservoir effect. The lacustrine Tauca phase started a little before 16,00014C yr B.P., and the lake level reached its maximum between 13,000 and 12,00014C yr B.P. A dry event (Ticaña) occurred after ca. 12,000 and before 950014C yr B.P. A moderate lacustrine oscillation (Coipasa event) occurred between ca. 9500 and 850014C yr B.P., using a reservoir-corrected conventional14C chronology. Comparisons between the lake-level chronology in the Uyuni-Coipasa basin and data from other southern tropical areas of South America suggest that the lacustrine evolution may reflect large-scale climatic changes.

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