Over time, waves erode a notch at the base of a cliff in a process called undercutting. When this notch becomes too heavy it will break off and crash into the sea. Different parts of the rock face are eroded at high and low tide. If high winds meet a high tide, the erosion will be greater. Different coastal features such as caves, arches and stacks are all formed by erosion.

First broadcast:
22 November 2007

In order to consolidate the key vocabulary related to this clip, pupils could be asked to label key features of pictures and diagrams of different coastlines. Making papier mâché, clay or plasticine models of coastlines featuring caves, arches and stacks could be a creative way to develop a clear understanding of coastal features. Pupils could then use these models to explain how different features are formed through the process of weathering and erosion. Alternatively, pupils could be given images of notches, caves, arches and stacks to identify and explain how each feature may have been formed.