Chronology of the Late Pleistocene Yellowstone Ice Cap

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ABSTRACTChronology of the Late Pleistocene Yellowstone Ice CapbyJoseph M. Licciardi and Mark D. Kurz An understanding of climatic linkages between western North America and the North Atlantic region is essential for identifying causes of abrupt climate variability in the Northern Hemisphere during the last glacial period (over the past ~21,000 years). Advances and retreats of alpine glaciers are sensitive indicators of changes in Ice Age climate. The former Yellowstone Ice Cap was the largest alpine glacier system in the western U.S., and the deposits it left behind preserve a valuable record of past climates in western North America. In prior research, we successfully established a high-resolution chronology of fluctuations of the northern Yellowstone outlet glacier. The initial investigation at Yellowstone, however, was restricted to a single drainage, and therefore did not resolve many aspects of the complex Yellowstone glacial history. Here we propose a further investigation of this important climate signal and its origin. We will apply isotopic dating techniques to glacial deposits in additional drainages within the Yellowstone region. The new results will greatly enhance current knowledge of the Yellowstone glacial history, and will provide an alpine glacial chronology of unprecedented resolution in the western U.S. An improved chronology of Yellowstone glaciation will enable a compelling and detailed comparison with alpine glacier records elsewhere in the western U.S., and with the timing of abrupt climate events in the North Atlantic region. Consequently, the improved chronology will strengthen and refine climatic interpretations derived from the glacial record, and will provide an important base of evidence for further evaluating the origin of millennial-scale climate variability in the Northern Hemisphere.