HR: 0800h
AN: C51A-0269    [Abstracts]
TI: Dynamic Response of Tidewater Glaciers During the Holocene, Glacier Bay, Alaska
AU: * Lawson, D E
EM: dlawson@crrel.usace.army.mil
AF: CRREL, 72 Lyme Road, Hanover, NH 03755 United States
AU: Alley, R B
EM: ralley@essc.psu.edu
AF: Pennsylvania State University, Dept. Geosciences and Environmental Systems Institute, University Park, PA 16802 United States
AU: Finnegan, D C
EM: David.Finnegan@erdc.usace.army.mil
AF: CRREL, 72 Lyme Road, Hanover, NH 03755 United States
AB: Despite the well-known, complex ice-dynamic and tectonic controls on tidewater-glacier behavior, correlations between past ice-marginal changes and climate changes suggest that the tidewater glaciers record important climatic information, with summertime insolation and temperatures important. Terminus positions of the tidewater glaciers in Glacier Bay are known reasonably well from radiocarbon dates on stumps rooted in growth position but overridden by advancing ice, and by limited stratigraphic data associated with them. The last glacial maximum (LGM) advance extended well beyond any Holocene position. The post-LGM rise in insolation and greenhouse gases was accompanied by retreat behind the present position prior to 12.5K C14 years BP. An early Holocene advance was initiated prior to 9K C14 years BP, after insolation began falling, and this advance passed the current marginal position by about 8.8-8.4K C14 years BP. The next, more-extensive advance was initiated prior to 5K C14 years BP, at a time when other paleoclimatic data indicate regional cooling and drying, emphasizing the role of summertime temperatures. The most extensive Holocene advance occurred during the Little Ice Age, consistent with the low insolation at that time. A possible interpretation of the observed behavior is that the ice responds to millennial climatic variability or non-climatic controls, within an envelope defined by the orbital control on summertime temperatures.
DE: 0720 Glaciers
DE: 0774 Dynamics
DE: 1621 Cryospheric change (0776)
SC: Cryosphere [C]
MN: Fall Meeting 2005