Exfoliation in Coquihalla Valley
April 22, 2003
The photo above show a classic example of exfoliation. The u-shaped Coquihalla valley in British Columbia, Canada was carved by glaciers tens of thousands of years ago. As the overlying glacial material was removed, the rocks that had formed underneath the massive ice-sheet "rose up" (isostacy) and tried to expand. Isostacy is also known as "glacial rebound." Rocks, of course, aren’t very flexible so instead of expanding, their outer layers are peeling off like onion skins -- the process of exfoliation.