HR: 0800h
AN: C51B-0294    [Abstracts]
TI: Modeling the evolution of the Cordilleran ice sheet in the Puget lowlands
AU: * Sheerer, R J
EM: sheerer@u.washington.edu
AF: Department of Earth and Space Sciences, Box 351310 University of Washington, Seattle, WA 98195-1310 United States
AU: Hallet, B
EM: hallet@u.washington.edu
AF: Department of Earth and Space Sciences, Box 351310 University of Washington, Seattle, WA 98195-1310 United States
AB: We develop a physically-based, numerical model of the advance of the Cordilleran ice sheet into northwestern Washington during the last glacial maximum in an effort to better understand the dynamic characteristics and associated geomorphic processes of the Puget Lobe. The modeling benefits from a wealth of geologic data reflecting the extent, flow direction, and timing of the advance and retreat of the Puget Lobe. The relevant physical processes include: rapid basal motion due to high basal water pressures, climate source-sink feedbacks, and isostatic depression/rebound, which influence local sea level and calving. The modeling of these small spatial-scale processes together with the large spatial extent of this system present a numerical challenge. Here, we have assumed a boundary flux of ice from Fraser valley in southern British Columbia, while using the shallow ice approximation and an empirical expression relating sliding speed to basal effective pressure to model ice flow. A climatic source function of ice surface elevation related to the expected equilibrium line altitude is also considered. Preliminary results already show that the model is instructive for 1) defining the principal processes and parameters values that control the advance and retreat, 2) understanding the magnitude of the climate shift that produced this glacial advance, and eventually, 3) for probing the evolution of other ice bodies.
DE: 0726 Ice sheets
DE: 0798 Modeling
DE: 1824 Geomorphology: general (1625)
SC: Cryosphere [C]
MN: Fall Meeting 2005