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.

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

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

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Recently weathered rock can be seen at the foot of chalk and limestone cliffs and is easily identified because it is angular.

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

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