Few long-term glacial records exist, and the ones that do are geographically scattered. The White Mountains, immediately east of the central Sierra Nevada in California and Nevada have one of the most complete sequences of deposits from glacial events in North America. New pre- and post-applications of new surface exposure dating methods make it possible to determine ages of geomorphic surfaces through analyses of multiple cosmogenic isotopes that accumulate in surface boulders. The goal of this collaborative project is to develop a numerical glacial chronology for the White Mountains using these surface-exposure dating methods in conjunction with dates based on associated volcanics, rock varnish, soils, and weathering. The investigators will use the same approach in the Sierra Nevada in order to an accurately compare the two records and to discriminate the effects of synoptic climatology versus tectonic history as controls on the glaciation of the mountain ranges. The research is anticipated to provide one of the most complete continental records of glacial events in North America. The results obtained also will provide a chronology for comparing a continental glacial record with other long-term records of continental and environmental change and with the well-established marine record. The study will use multiple and varied dating techniques, some of which are in the intial stages of development, to help unravel the glacial chronology of the White Mountains. This interdisciplinary research effort will help assess the viability of new dating approaches and various traditional glacial, soils, and geomorphological techniques used by physical geographers and other earth scientists. The research will contribute to our understanding of how the well-preserved glacial sequence in the White Mountains relates to changes in climate, tectonic activity, and vegetation. The study will correlate the White Mountain glacial sequence to other regional continental geomorphic investigations and to the lengthy glacio-marine record, and it will provide insight into the scale and timing of large changes in the hydrologic balance of the Western United States.
