When the water freezes, it expands in volume by 9%, exerting a tensional force that widens the rock
Thawing allows more water to enter the crack, and the process repeats until cracks are forced open large, angular pebble, cobble, or boulder-sized fragments are loosened off.
Any rocks with cracks and fissures are vulnerable to it, especially high on cliffs away from sea spray.
Freezing is relatively uncommon on UK coasts.
Salt Crystal Growth
When salt water evaporates it leaves salt crystals behind
These grow over time and exert stress in the rock, causing it to break up
Salt also corrodes rock with iron in
Wetting and drying
Rocks rich in clay (shale) expand when wet and contract when dry - causing them to crack and break up
