HR: 1340h
AN: U33A-0007    [Abstracts]
TI: Measuring the Retreat Velocity of the Laurentide Ice Sheet by Cosmogenic Nuclides? Be-10 Dating of Glacial Features in Lower Hudson Valley
AU: * Steinberg, R
EM: rs2175@barnard.edu
AF: Lamont-Doherty Earth Observatory, Gechemistry, Palisades, NY 10964 United States
AU: Kelly, M
U33A-0007 AF: Lamont-Doherty Earth Observatory, Gechemistry, Palisades, NY 10964 United States
AU: Schaefer, J M
EM: schaefer@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Gechemistry, Palisades, NY 10964 United States
AU: Rinterknecht, V
U33A-0007 AF: Lamont-Doherty Earth Observatory, Gechemistry, Palisades, NY 10964 United States
AU: Schwartz, R
U33A-0007 AF: Lamont-Doherty Earth Observatory, Gechemistry, Palisades, NY 10964 United States
AU: Balco, G
U33A-0007 AF: University of Washingtong, Quaternary Research Center, Seattle, WA 98915 United States
AB: The Laurentide Ice Sheet (LIS) was the earth's dominant continental ice sheet during the Last Glacial Maximum (LGM). The LIS deglaciation represents a dramatic environmental change that released enormous amounts of fresh water to the Atlantic Ocean, potentially inhibiting the North Atlantic Deep Water formation, thus affecting the thermohaline ocean circulation and global climate. To evaluate the impact of this fresh-water signal, it is important to determine the timing and rate of the LIS retreat, particularly along the Eastern margin of the United States. Glacial geologic features in the Lower Hudson Valley region provide evidence of the advance of LIS to its LGM terminus at Long Island and the subsequent ice recession. The surface exposure dating method using the cosmogenic nuclide Be-10 is applied to date glacially transported erratic boulders and scoured bedrock in two areas, Black Rock Forest and Harriman State Park, in the Lower Hudson Valley. We compare these Be-10 dates with numerous Be-10 dates from the terminal moraine on Long Island (Harbor Hill Moraine) and its extension in Connecticut (Charlestown Moraine). The goal of this project is to develop a chronology of the recessional ice margin. A comparison of Be-10 dates from the terminal moraine at Long Island with those located in the Lower Hudson Valley region yields a first order measure of the rate of the LIS retreat.
DE: 0726 Ice sheets
DE: 1105 Quaternary geochronology
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1641 Sea level change (1222, 1225, 4556)
SC: Union [U]
MN: Fall Meeting 2005