Cosmogenic isotope studies of glacial erosion

The presence of abundant cosmogenic radioactive isotopes in rock under one of the large modern ice sheets demonstrates strong non-steadiness—the ice must have gone away to allow cosmic-ray bombardment (Nishiizumi et al., 1996). Mapping such exposure would provide possibly the strongest constraints on the history of ice-sheet existence and stability/instability. Access-hole boring followed by shallow drilling into rock and careful analysis ofthe samples recovered should be sufficient. This also would allow geothermal-flux determination, providing a critical but poorly known boundary condition for ice-flow modelling.

Glacial erosion of mountain belts is of interest, and figures in some discussions of global biogeochemical cycling, etc. Among the many questions that can be addressed is whether, in partially glaciated basins, the erosion is primarily beneath the ice or

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