A corrie is a deep armchair-shaped hollows found in the side of mountains.
An arête is a ridge that forms between two corries that form beside each other.
A pyramidal peak is produced when there are corries on all sides of a mountain, giving the peak a sharp appearance.

Corries are formed where glaciers begin.
Corries are formed when snow in high altitude regions becomes compacted and dense.
When the ice moves away due to gravity, it carves out a section of the mountainside.
It does this through the action of plucking on the back wall.
The rotational force of the ice causes greater pressure on the base of the hollow.
Corries usually form on the side of the mountain that receives the least sunshine due to the lower temperatures. In the UK, this is usually the northeast side of mountains.

Corries have deep depressions when glaciers begin to move away. These can fill with water to form glacial lakes.