The Extent of Early Versus Late Wisconsin Glaciation: A Test Using Cosmogenic 36C1 Dating

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Cosmogenic chlorine-36 buildup dating is a new geochronological method that measures how long a rock has been exposed to cosmic rays on the earth's surface, rather than the time since it became a geochemically closed system. The method can thus be used to date the construction of landforms, such as glacial moraines, that are difficult or impossible to date using conventional methods. This award supports glacial chronology investigations by cosmogenic 36Cl buildup at four locations (1) measurements on samples from Mauna Kea, (2) the Wind River Range, Wyoming, (3) Banks Island, NWT. Canada, and (4) one other site in the High Arctic. These sites will provide a latitudinal transect of the northern hemisphere to test whether the chronological pattern previously observed at Hawaii and the Sierra Nevada was due to coincidental local anomalies or to truly global climate effects. One potential implication of a positive result would be that the growth of continental-scale ice caps may be more a response to internal dynamics than global climate forcing.