Tectonic Geomorphology Spring 2008
Instructors: Ramon Arrowsmith and Kelin X. Whipple
Warm-up question for first weekend.
1. Isostatic Compensation of Ice (20 pts).
In class we discussed isostasy in very general terms as a function of the relative densities of a
solid floating in a liquid. In lab you used this concept to calculate the subsidence of oceanic
lithosphere with time as it cools and thickens. Here you will do an analogous calculation for a
block of ice (i = 0.9 gcm-3) floating in water (w = 1.0 gcm-3).
1A. Explain the concept of Isostasy (5 pts).
1B. If the top of a block of ice (simple rectangular prism geometry) rises 10m above the
surrounding water, how far below the water surface is the base of the block of ice? (5 pts).
1C. Assume that over the course of a warm week that 9m of ice is sublimated and/or melted off
the top of the block of ice (assume no melting of the submerged ice). Describe what happens.
At the end of this warm week, how high does the top of the block of ice rise above the water? (10
pts).
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