Old Harry Rocks in Dorset stand at the tip of a chalk headland between the bays of Studland and Swanage. Chalk is made up of the fossilised remains of single-celled organisms which lived in the sea. Over thousands of years, millions of fossils became compressed to form the rock. As sea levels fell, the chalk became exposed. Old Harry Rocks form a headland as the chalk is more resistant to erosion than the surrounding clays. With thanks to the British Geological Survey. Ordnance Survey mapping © Crown Copyright.

Students could study landforms along an area of coast near to them. Use maps, images or a field trip to work out where there are differences in the hardness of rocks. Students could check their findings by over-laying OS and geological maps. Students could then consider how the coast and rocks may change in the future.