Glaciers create basins called corries (cirques/cwms):
- glaciers normally form on one side of a montain peak - the side that gets the least sun and the coldest winds. That's where there's most accumilation and least ablation
- Snow collects in hollows and turns int ice. Basal sliding (rotational flow) with abrasion and plucking deepen the hollow into a corrie (bowl-shaped hollow)
- When the ice in the hollow is thick enough, it flows over the lip and downhill as a glacier. Forst shattering and plucking steepen the back wall of the corrie.
Glacial erosion changes the landscape of valleys:
1) An arete is a steep sided ridge - it's formed when two glaciers flow in parallel valleys. The glaciers erode the sides of the valley, which sharpens the mountain ridge in between them
2) A pyramidal peak is a pointed mountain peak with at least three sides. It forms where three or more corries form back to back.
3) Glacial troughs (U-shaped valleys) are steep-sided valleys with flat bottoms. They're formed by the erosion of V-shaped river valleys by glaciers. As the glacer erodes through the V-shaped valley it makes them deeper and wider.
4) Hanging valleys are valleys formed by tributory glaciers - they erode the valley floor much less deeply as they're smaller than the main glacier. So, when the glaciers melt, the valleys get lef at a higher level than the glacial trough form dby the main glacier. Waterfalls occur at hanging valleys into the main glacial trough.