THE HISTORY OF GLACIAL LAKE WASHBURN, TAYLOR VALLEY, ANTARCTICA

During the last glaciation the Ross Ice Sheet (RIS) advanced into the McMurdo Sound and dammed a large pro-glacial lake (Glacial Lake Washburn; GLW) in Taylor Valley, Antarctica. Despite its importance for understanding the history of this region, the history of GLW and the RIS expansion into Taylor Valley are convoluted and, in many cases, published works contradict one another. Although the distribution of the RIS drift in Taylor Valley is largely not debated, some argue that the drift was distributed by the RIS itself, while others state that it was spread throughout the valley by lake ice processes atop GLW. Fluctuations in GLW lake levels are attributed by various authors to ice-sheet-movement driven changes in basin size, paleoclimate driven changes in water balance, or both. Perched deltas throughout Taylor Valley at various elevations are thought to be indicative of these changes in GLW lake levels. However, strandlines, which provide the main line of evidence linking the perched deltas to the same water body, are a subject of debate, with some interpreting well-developed terraces as slump-derived strandlines, and others interpreting strandlines as weakly developed horizontal features etched into the valley walls in some locations, referring to the former as moraines. The well-developed strandlines suggest much larger, deeper GLW than are indicated by the weakly developed alternative. Here, we synthesize existing data concerning GLW to form a more up to date hypothesis on the history of Taylor Valley during the last glaciation.