Weathering

Exposed rocks along the coastline can be broken down by the processes of weathering.

Freeze-thaw weathering

Freeze-thaw weathering occurs when rocks are porous (contain holes) or permeable (allow water to pass through).

Water enters crack in rock. Water freezes and expands, widening crack. Ice melts and water goes deeper into crack. Process repeats until rock splits.
  1. Water enters cracks in the rock.
  2. When temperatures drop, the water freezes and expands causing the crack to widen.
  3. The ice melts and water makes its way deeper into the cracks.
  4. The process repeats itself until the rock splits entirely.

Biological weathering

Plants and animals can also have an effect on rocks. Roots burrow down, weakening the structure of the rock until it breaks away.

Roots enter small crack in rock. As roots grow, crack gets larger. Rock breaks away.
  1. Plant roots can get into small cracks in the rock.
  2. As the roots grow, the cracks become larger.
  3. This causes small pieces of rock to break away.

Chemical weathering

Rainwater and seawater can be a weak acid. If a coastline is made up of rocks such as limestone or chalk, over time they can become dissolved by the acid in the water.

An image of chemically-weathered limestone
Chemically-weathered limestone