| Department Colloquium |
Wednesday
April 12, 2006
Science Center 170
2:00—3:00 p.m.
Lunch: 12:00 in
Buntrock Commons #221
Phone: 507-646-3120
email: russell@stolaf.edu
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"Glacier Sliding and Bed
Erosion: Experiments beneath the Svartisen Ice Cap, Norway"
Neal Iverson
Dept. of Geological and
Atmospheric Sciences
Iowa State University
Wet-based glaciers can move primarily by sliding over
their beds. This sliding is responsible for rapid ice-sheet movement and can
hasten ice-sheet disintegration. Glacier sliding also causes bedrock erosion
and hence is responsible for some of the most spectacular landforms on Earth.
Sliding and erosion experiments were conducted beneath 215
m of ice at the bed of Engabreen, an outlet glacier of the Svartisen Ice Cap,
where tunnels through subglacial bedrock provide human access to the bed of a
thick sliding glacier. Results of two different types of experiments there
indicate that classical glacier-sliding models that ignore basal debris require
revision and that rates of bedrock erosion are sensitive to hydraulic
transients and associated ice-bed separation. These are the first measurements
in real time of subglacial sliding friction and bedrock erosion.
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