Glacial Deposition
As a glacier moves downhill, temperatures rise and the glacier begins to melt, depositing the material it has been carrying to lowland areas. Ice melts most quickly at its edges, where it is thinner. That’s why glaciers start to melt at their lower ends. Huge boulders, coarse rubble, and fine clay particles are all deposited together when the ice melts. Moraine, is the name given to the rock material carried by the glacier and there are a number of different types of moraine according to when and where they were deposited by the glacier.
Drumlins, Cato, New York
Another distinct landscape feature of glacial deposition is drumlins. Drumlins are egg-shaped hills that can be more than 45m in height and 0.8 km long. Deposited by glaciers and shaped by the moving ice, drumlins are mounds of boulder clay.
Not all glaciers move slowly. For example, surging glaciers experience dramatic increases in flow rate, sometimes traveling as much as ten to one hundred times faster than the normal rate of movement.
Rocks transported many miles by a glacier and later found in an area of a different rock type are called erratics. On the east coast of England, erratic blocks can be found which are comprised of rocks found in the Norwegian highlands.
Svartisen Glacier, Norway
Each year a glacier will melt in the summer and refreeze in the winter. The process of glaciers growing is called the accumulation and glaciers that are growing are said to be advancing. The Svartisen glacier in Norway is a good example of an advancing glacier, but there examples everywhere.
Some glaciers are melting, reducing in size and this process is called ablation. Glaciers that are reducing in size are said to be retreating and these are in the majority.
Grinnell Glacier, USA
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