- can occur by freeze-thaw or frost shattering
The freeze-thaw cycle:
- Rainwater becomes trapped in a joint/crack in a rock
- At night the temperature goes below 0c, the water then freezes and expands
- In the morning air temperature rises above 0c so the water melts. Due the expantion of the water when it froze, the joint/crack in the rock widens slightly.
- After repeated freeze-thawing, the rock gradually weakens and eventually it will split.
- physical weathering can also occur by pressure release. Rocks sutch as granite cool deep in the Earths crust under very high pressures. When exposed on the surface, as on Dartmoor, the pressure is released and many horizontal and vertical joints and weaknesses develop in the rock.
- Rainwater passing through the atmosphere absorbs Carbon Dioxide and becomes a…