Cirques – also called ‘corries’ and known as the birthplace of a glacier – are found high up in the mountains. A cirque has three steep sides and may contain a lake.
Formation 1
Snow collects in a mountain hollow high up in the mountain. With repeated snowfalls, the snow compacts to form ice. A glacier is born.
2
Through plucking and abrasion, the hollow grows deeper. Freeze-thaw action is also at work here. (Look back at Chapter 8 to remind yourself of ‘freeze-thaw action’.)
Rock weakened by freeze-thaw weathering
Plucking Abrasion 3
Glacier moving out of cirque
When the glacier is big enough, it begins to flow over the edge of the cirque. It then begins its journey down the valley.
4
When the glacier melts, a lake called a tarn may be trapped in the cirque hollow.
Tarn
Arête
5
When two cirques form back to back, the ridge between them is known as an arête.
Examples: The Devil’s Punchbowl, Co. Kerry, and Coumshingaun in the Comeragh Mountains, Co. Waterford.
