Glacial evidence in the UK

One problem with teaching glaciers, is that we are no where near a glacier and so it is difficult to enthuse students about glaciers. Glaciers have no immediate effect on our lives. However as some of us know, this is not the case as evidence of a glacial past is in the UK, especially in the Lake District.

This is a Corrie called Red Tarn in the Lake District.

Snowflakes collect in a hollow. As more snow falls, the snow is compressed and the air is squeezed out to become firn or neve. With the pressure of more layers of snow, the firn will, over thousands of years, become glacier ice. Erosion and weathering by abrasion, plucking and freeze-thaw action will gradually make the hollow bigger.

Even though the ice is trapped in a hollow and unable to move down hill, gravity will still encourage it to move. This circular motion is known as rotational slipand can cause the ice to pull away from the backwall creating a crevasse or bergschrund. Plucked debris from the backwall causes further erosion through abrasion which deepens the corrie.

Some of this debris is deposited at the edge of the corrie, building up the lip.

These processes create a characteristic rounded, armchair shaped hollow with a steep back wall.

When ice in a corrie melts, a circular lake is often formed at the bottom of the hollow.

This description ts taken from BBC Bitesize, where there is also a diagram demonstrating the formation of a corrie.

http://www.bbc.co.uk/schools/gcsebitesize/geography/glaciation/glacial_erosionrev1.shtml