Results

The results of 21 model runs that tested model sensitivity to input parameters enabled Cutler et al. (2000) to respond in general terms to the three fundamental questions posed at the outset.

How deep was ice-marginal permafrost under the Green Bay Lobe? At its maximum, permafrost thickness may have approached 200 m—the average thickness of the aquifer in Wisconsin. Its thickness was always at least a few tens of metres up to the Last Glacial Maximum (LGM).

How wide was the subglacial frozen zone during ice advance? The frozen zone upstream from the ice margin extended 60 to 200 km at the LGM.

How quickly does subglacial permafrost thaw once overridden? The answer depends primarily on the thickness of the permafrost before it is overridden. In the case of the Green Bay Lobe, it lasted for centuries to a few thousand years under advancing ice.

0 0

Post a comment