Glaciated Upland Landscapes Flashcards
How does ice erodes
The base of glacier ice melts because of pressure and friction. This allows water to freeze into cracks in the rocks and when the glacier moves it pulls out chunks to leave a jagged surface. This provides material for abrasion and this process is called plucking. Rocks which get stuck in the ice grind away the bedrock under the glacier and this is known as abrasion. Freeze thaw, or frost shattering, is a process of weathering that also occurs in upland areas. Water in cracks in the rock freezes and expands, forcing open the gap. When the ice melts more water can get into the crack and freeze again.
Formation of a glaciated upland features
A corrie is an armchair shaped hollow high on a mountain with steep back and side walls. Snow gathers in mountain
hollows especially north facing hollows, where there is more shade. This snow builds up and compacts to ice. The action of gravity means the ice moves downhill. As it travels, ice sticks to the back walls and plucks rocks from the surface. Rocks on the back walls are also loosened by freeze-thaw action. A gap between the wall and the ice develops, called a
bergschrund.
What is an arête
An arête is a knife-edge ridge It is formed when two neighbouring corries run back to back. As each glacier erodes either side of the ridge, the edge becomes steeper and the ridge becomes narrower.
What is a pyramidal peak
A pyramidal peak is formed where three or more corries and arêtes meet. Glaciers erode backwards towards each other, carving out the rocks by plucking and abrasion. Freeze thaw weathers the top of the mountain, creating a sharply pointed
summit.
what is a u-shaped valley
