Different types of Weathering

Freeze thaw:
Where does it occur?
In mountainous regions like the Alps or Snowdonia.

How does it occur?
Rainwater or snow-melt collects in cracks in the rocks.

At night the temperatures drops and the water freezes and expands.

The increases in volume of the ice exerts pressure on the cracks in the rock, causing them to split further open.

During the day the ice melts and the water seeps deeper into the cracks.

At night the water freezes again….etc.

Onion skin:
rock is repeatedly subjected to heat and cold
outer layer expands in heat
outer layer contracts in cold
outer layer of rock peels off (loose rock known as scree)

Biological:
Animals and plants can wear away rocks. This is called biological weathering. For example, burrowing animals such as rabbits can burrow into a crack in a rock, making it bigger and splitting the rock.

You may have seen weeds growing through cracks in the pavement. If you have gone for a walk in the countryside, you may even have seen bushes or trees growing from cracks in rocks or disused buildings. This is because plant roots can grow in cracks. As they grow bigger, the roots push open the cracks and make them wider and deeper. Eventually pieces of rock may fall away.

People can even cause biological weathering just by walking. Over time, paths in the countryside become damaged because of all the boots and shoes wearing them away.

Chemical:
Chemical weathering changes the composition of rocks, often transforming them when water interacts with minerals to create various chemical reactions. Chemical weathering is a gradual and ongoing process as the mineralogy of the rock adjusts to the near surface environment. New or secondary minerals develop from the original minerals of the rock. In this the processes of oxidation and hydrolysis are most important.
The process of mountain block uplift is important in exposing new rock strata to the atmosphere and moisture, enabling important chemical weathering to occur; significant release occurs of Ca++ and other minerals into surface waters.