Freeze-thaw weathering occurs when rocks are porous (contain holes) or permeable (allow water to pass through). Water enters the rock and freezes. The ice expands by around 9%. This causes pressure on the rock until it cracks. Repeated freeze-thaw can cause the rock to break up.

Find out more about weathering.

Mechanical weathering is the breakdown of rock without changing its chemical structure (composition).

Find out more about weathering.

Chemical weathering is the breakdown of rock through changing its chemical composition.

Find out more about weathering.

Salt weathering is when salt spray from the sea gets into a crack in a rock. It may evaporate and crystallise, putting pressure on the surrounding rock and weakening the structure.

Find out more about weathering.

Weathering is the breakdown of rock in situ by the action of rainwater, extremes of temperature, and biological activity.

Find out more about weathering.