Process which allows glaciers to erode bedrock surfaces via a three stage progression In the first stage (a ), meltwater at the base of the glacier seeps into cracks in the bedrock Once collected in these fractures, the water freezes and expands, further fracturing the rocks and making bedrock debris available to the glacier (b) This debris is then removed either by freezing to the bottom of the glacier or by being dislodged by rocks projecting from the bottom of the ice (c)
Erosive process of particle detachment by moving glacial ice In this process, basal ice freezes in rock surface cracks As the main body of the glacial ice moves material around the ice in the cracks is pulled and plucked out Also called quarrying