What is mechanical weathering? How does freezing action of water affect weathering of rocks?

Mechanical weathering involves disintegration of rocks without the change in their chemical composition. It is mainly brought about by:

1. Changes in temperature
2. Freezing action of water

Freezing action of water — In mountainous regions or in areas with cold climate, the breaking of rocks is caused by the freezing action of water. The cracks and joints in the rocks fill up with water. At night, when the temperature falls, the water in the cracks or joints freezes. The conversion of water into ice increases its volume, thereby requiring more space. This causes widening of cracks and joints and finally leads to their disintegration. This is also called frost action.