As glaciers extend across a landscape, they pick up unconsolidated sediments from the ground and transport them. Other sediments may be deposited onto a glacier's surface layer from nearby debris falls. In addition, a glacier may erode nearby surfaces and incorporate material into its mass.
As a glacier continues to move, it pushes any collected debris forward. When a glacier reaches its final (terminal) location, the glacial front (terminus) deposits some of this debris in a ridge-like formation called a terminal moraine. After the glacier retreats, it leaves behind the moraine.
Scientists study terminal moraines to infer the maximum extent of specific glaciers. Multiple terminal moraines in a single area hints at multiple glaciations in descending advance. (If a terminal moraine exists behind another terminal moraine, the second glacial advance was not extensive enough to wipe out the old land form.) Other types of moraines include medial moraines, lateral moraines, and ground moraines.
No comments:
Post a Comment