1. In some areas, the temperataure is above 0 degrees celcius during the day, and below 0 degrees celcius at night.
2. During the day, water gets into cracks in rocks, e.g granite
3. At night, water freezes and expands, which puts pressure on the rock
4. The water thaws the next day, releasing the pressure, then refreezes the next night
5. Repeated freezing and thawing widens the cracks and causes the rocks to break up
Exfoliation: flaking of the outer surface of rocks mainly caused by repeated cycles of hot and cold.
1. Some areas have a big daily temperature range, e.g. dessets
2. Each day the surface layers of rock heat up and expand faster than the inner layers
3. At night the surface layers cool down and contract faster than the inner layers
4. This creates pressure within the rock and causes thin surface layers to peel off
Chemical weathering: the process where chemical reactions change or destroy minerals when rock comes into contact with water and air.
1. Some minerals that make up rocks are soluble in water
2. The minerals dissolve in rainwater, breaking the rock down
1. Rainwater has carbon dioxide in it, which makes it a weak carbonic acid
2. Carbonic acid reacts with rocks that contain calcium carbonate, so the rocks are dissolved by the rain water
Biological weathering: weathering caused by living things such as tree roots or burrowing animals.
1. Plant roots break down rocks by growing into cracks on their surfaces and pushing them apart
2. Burrowing animals may loosen small amounts of rock material