Landforms created by glacial deposition are often found in much lower altitudes in lower valleys. They are found in areas where the temperature is warmer so the ice melts and loses its capacity to carry material. The major features include erratics, drumlins and different types of moraine.
Erratics are large boulders that sit on top of a different type of rock on the landscape. They have often been transported huge distances by the ice and deposited far from their bedrock of origin. Ice transported boulders are similar, but are still found on their bedrock of origin. The Bowder Stone in Borrowdale, Cumbria is a 2,000 ton erratic thought to originate in Scotland.
Moraine – This is the material produced by glacial erosion. The material tends to be unsorted (it contains really huge boulders and at the same time a fine powder called glacial flour). It also tends to be very angular, as the processes that form the material involve freezing and shattering.
Aerial view of medial glacier moraines, Nuussuaq Peninsula, Greenland. By Algkalv (Own work)
There are different types of moraine including:
Moraines in New Zealand
A drumlin is a hill of compact, unsorted glacial till, usually oval in shape, with the long axis showing the former glacial motion.
The most identifying characteristic of drumlins are their shape, resembling an inverted spoon with its steep slope facing the direction from which the ice advances. Drumlins can be up to 7 km in length, 2 km in width and 30 m in height.
They are thought to form where material is deposited underneath a glacier as ground moraine. This material is then shaped into the drumlin shape as the ice advances or retreats. Running water under the ice could also play a role in helping shape the drumlin.
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