Geography Nat 5 Glaciation

Corrie

Snow collects in a North facing hollow, compresses and turns to glacial ice. Due to gravity and its own weight, the glacier begins to move down hill. Freeze thaw action losses rock fragments which get trapped in the bottom and the sides of the glaciers. Abrasion creates a deep armchair shaped hollow using rocks embedded in ice. Plucking creates a steep back wall as the glacier moves downwards.

Freeze thaw action

Melt water from the glacier enters crackd in the rock. As it freezes it expands the gap. This happens again and again lossening shards of rock that can freeze onto the base and sides of the glacier.

Plucking

The glacier becomes stuck to rock when the glacier moves it rips fragments of rocks away. This leaves behind a jagged rock face.

Abrasion

Rocks plucked away by the glacier become embedded in the glacier as the glacier moves these rocks scrape and smooth the landscape like sandpaper.

Arête

Snow collects in a North facing hollow, compresses and turns to glacial ice. Due to gravity and its own weight, the glacier begins to down hill. The glacier erodes through abrasion this is when rocks plucked by the glacier become embedded in the ice and scrape and smooth the rock like sandpaper. It creates a steep jagged back wall through freeze thaw action this is when melt water gets into cracks freezes and expands causing small rock fragments to break away. When 2 corries form back to back they create a knife- like ridge called an arête.

Pyramidal Peak

Snow collects in a North facing hollow, compresses and turns to glacial ice. Due to gravity and its own weight, the glacier begins to down hill. The glacier erodes through abrasion this is when rocks plucked by the glacier become embedded in the ice and scrape and smooth the rock like sandpaper. It a steep jagged back wall through freeze thaw action this is when melt water gets into cracks freezes and expands causing small rock fragments to break away. When 3 or more corries form back to back the rock between them was plucked and weathered into a sharp point this dharp point is called a pyramidal peak.

U-shaped valley

Snow collects in a North facing hollow, compresses and turns to glacial ice. Due to gravity and its own weight, the glacier begins to move down hill. The glacier flows through an existing v-shaped valley. Where it bulldozes through interlocking spurs by erosion. It does this by abrasion this means that fragments of plucked rock embedded in the glacier abraded the landscape like sandpaper leaving it smooth. It also erodes by plucking this is when the glacier sticks to the rock and as it moves it rips away fragments of rocks. This forms a u-shaped valley with a flat valley floor and steap sides.