How do glaciers transport material?
A glacier transports material above, below and within it.
As ice flows down from upland to lowland areas, the material is pushed along by the snout (front) of the glacier. The sheer force of the ice pushes soil, rocks and boulders. Also, the material is transported on top of the glacier. Freeze-thaw weathering on the back wall of a corrie or along the sides of the valley above the glacier causes rocks to become detached and fall onto the glacier.
Meltwater flows from the snout of the glacier and can transport moraine away from the glacier. This is often deposited on the outwash plain of the glacier. Outwash plains are made up of outwash deposits and are characteristically flat and consist of layers of sand and other fine sediments. The image below shows an outwash plain in Iceland.
Rock debris is also carried within the glacier. This happens because plucking pulls rocks away along the floor and the glacier’s sides, which become embedded within the ice. Also, rock debris can fall into a crevasse at the surface of a glacier. This can get trapped within the body of the glacier.
When two glaciers meet side by side, forming a single glacier, material frozen to the edge of each glacier is trapped in the centre. This is called medial moraine. When the glacier melts, this material forms a small ridge of material running down the centre of the valley floor.
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