1. Wave erosion along a line of weakness produces a cut called a notch on the coast.
2. The notch is further eroded to form a cave, a hallow with an opening in a mass of rock.
3. Further erosion causes the overhanging part of the cave to collapse into the sea and a cliff is left behind.
4. Continuous erosion causes the cliff to move back or retreat inland. Over time, a wave-cut platform is formed at the foot of the cliff.
FOR ANIMATION DIAGRAM, GO TO http://www.bbc.co.uk/schools/riversandcoasts/coasts/change_coast/pg_07_flash.shtml