Corries, Arêtes, Pyramidal Peaks

Corries:

Found in: Glaslyn, Wales

Layers of snow build up on the Northface of a slope and do not melt during the summer this means that the layers of snow compress over many years into glacial ice. 

Due to gravity the glacier moves downslope by rotational movement depositing moraine at the end leading to the formation of a rock lip. When the ice melts a shallow armchair shaped hollow is left this can fill up with rainwater forming a corrie lake.

Arête:

Found: Crib Goch, Wales

These are formed when two corries form back to back leaving a steep knife-edged ridge 

Pyramidal peaks:

Found: Snowdon, Wales

Rare because it is rare to have corries forming on the south-facing slope, but it is where three corries form back to back.