An erosion feature

In the exam,you may have to explain how a erosion feature is formed. We have studied glaciation in the Lake District.

For a glacier to form we need:

• Long winters.




• Short summers.




• High amounts of snowfall.




• North facing accumulations of snow.

Snow builds up in hollows and compacts due to its weight into ice. As it builds up, it begins to move slowly downhill due to gravity. As a result of this movement, the glacier erodes by abrasion, scraping the sides of the valley, plucking, the glacier freezing onto the sides of the valley and as it moves forcing rock from the valley sides, and finally freeze thaw action. This is when water freezes at night, expands and melts during the day. After a while the rock cracks creating screes on the valley sides.

When the glacier eventually melts it leaves behind an armchair shape (armchair hollow) called a Corrie. This can have a small lake in it or Tarn eg Red Tarn, Helvellyn, Lake District.
The eroded rock and material is called Moraine