<P> Large masses , such as ice sheets or glaciers , can depress the crust of the Earth into the mantle . The depression usually totals a third of the ice sheet or glacier 's thickness . After the ice sheet or glacier melts , the mantle begins to flow back to its original position , pushing the crust back up . This post-glacial rebound , which proceeds very slowly after the melting of the ice sheet or glacier , is currently occurring in measurable amounts in Scandinavia and the Great Lakes region of North America . </P>
<P> Large masses , such as ice sheets or glaciers , can depress the crust of the Earth into the mantle . The depression usually totals a third of the ice sheet or glacier 's thickness . After the ice sheet or glacier melts , the mantle begins to flow back to its original position , pushing the crust back up . This post-glacial rebound , which proceeds very slowly after the melting of the ice sheet or glacier , is currently occurring in measurable amounts in Scandinavia and the Great Lakes region of North America . </P>
explain the behavior and activity of a retreating glacier
explain the behavior and activity of a retreating glacier
proceeds very slowly after the melting of the ice sheet or glacier
proceeds very slowly after the melting of the ice sheet or glacier