Monday, 12 September 2011

Morraines

Aim: To be able to understand the concept of a Moraine.

Once glacial ice has melted, a variety of rocks are laid down that have been carried down by the glacier. Piles of this material is named Moraines. They are usually seen as lines, or a series of mounds running across glacial valleys.

There are many types of moraines (See figure 1) ; the main types are terminal or end moraine which are found at the snout of the glacier.




Figure 1: Diagram illustrating the different types of moraines. (Source: Reference)

Terminal Moraines:

  • Consist of a material ridge stretching across a glacial valley
  • they are elongated at right angles to the direction of the ice advance
  • often steep sided and can reach heights of 50-60m
  • often crescent shaped, moulded to the form of the snout
  • formed from unsorted ablation material when the ice melts and the carried material has been deposited (Therefore they contain a variety of material)

As a glacier retreats, a series of moraines may be formed along the glacial valley, marking points where the retreat may have paused. (Recessional Moraines)


When the climate cools down, a glacial advance will occur and the previously deposited moraine may be shunted up into a mound known as a push moraine. 




Now test your knowledge with a quick quiz!! 


Quiz

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