Glaciation Flashcards
FORMATION OF A CORRIE
In the ice age, snow would gather in north facing hollows on the sides of mountains. As snow piled up, air from the bottom layers was pushed out due to the weight and eventually formed ice. As more snow kept building up, it filled the hollow and eventually moved out of the hollow and down the mountain due to gravity and this was the start of a glacier. The hollow was steepened by the process of plucking. This was when rocks froze onto the glacier and were ripped out of the wall as it began to move. The wall was also steepened by freeze - thaw weathering. This was when water would seep into cracks in the hollow and freeze. When water freezes it expands so the cracks would get pushed apart and deepened. After repeated expansion and contraction, rocks would fall off steepening the back wall. the base of the hollow would be deepened through the process of abrasion. Abrasion was when rocks would freeze onto the bottom of the glacier and as the glacier move out of the hollow, would act as sandpaper on the base and leave a smooth surface. This hollow then became a corrie. A corrie loch was then left in the base of the corrie
FORMATION OF AN ARÊTE
Two corries meat back to back. (formation of a corrie)
The ridged rough edge that was left was exposed to freeze thaw weathering. The edge became steeper as the corries became larger and the edge was called an arête.
FORMATION OF A PYRAMIDAL PEAK
This was when three corries met back to back. (formation of a corrie). Arêtes separated the corries at the top a steep sided peak was formed which was the pyramidal peak which was exposed to freeze thaw weathering.
FORMATION OF A U-SHAPED VALLEY
Before the ice age, rivers flowed down narrow v-shaped valleys. As glaciers moved out of the corries and down the mountain, they took the easiest route which was down the v- shaped valley. The ice was so thick it was able to change the shape and size of the valley by eroding it. (Three processes). The valley then gradually took a U-shape which steep sides and a flat floor. Rivers are now flowing through them again but they are too small for the huge valleys and are now called misfits streams. Some valleys were over eroded and and are now filled with water called ribbon lakes.
