Flow Reconstruction

As discussed in the section on glacier modeling above, ice is a material with highly predictable flow behavior. As such, if the geometry of the ice mass is known or can be reconstructed, its rate of deformation (a major component of flow) can also be determined. In a regionally-honored M.S. thesis, Don Murray (Murray and Locke, 1989, Journal of Glaciology, 35, 183-190) applied this principle to a glacier in the Crazy Mountains of western Montana. He found that:

1. glacier flow can only be reconstructed reliably for simple, linear glaciers,
2. glacier flow can only be reliably reconstructed for glaciers of constant slope, and
3. glacier deformation varies by a factor of ten along the glacier length.

However, by assuming that sliding is zero where the maximum deformation flux is observed (relative to a continuity correction above and below the ELA), he generated a conservative estimate of the mass flux at the last glacial maximum. This estimate is about 25% less than current maximum annual snowpack, suggesting drier conditions at the last glacial maximum than at present. The methodology has potential for application in other areas where glaciers of suitable morphology can be found.

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