Here, on Canada's Baffin Island, an isolated angular block of schist debris is balanced above the ice surface on a "tee" of shaded ice.  Clearly, the source of that block was a rock slope similar to the ones in the background.  The effectiveness of a thin debris cover in enhancing absorption of solar energy, thus of increasing melt, is evident in the height of the "tee".  In the background a medial moraine rises above the glacier surface.  Part of that elevation is ice, which melts more slowly under a thick, insulating cover of debris than does adjacent bare ice.  The meltwater stream in the foreground winnows some of the fine sediment out of the till, but the coarse fraction will be carried to the termius before the ice melts out and the debris is deposited as till.
 

Thumbnails, photos, and annotated photos copyright W. W. Locke, 1998; all rights reserved.