lithosphere

• Snow accumulates in north facing hallows when more snow falls in winter and then melts in the summer.  Plucking is when ice freezes on to bedrock, pulling loose rocks away from the sides. Abrasion is when the angular rock embedded in the ice grinds the valley floor, as the glacier moves. Freeze thaw weathering is when water in cracks in the rock freezes, expands and contracts weakening the rock until fragments break off.