- In the glacial period 10,000 years ago the ground was frozen, including the underlying chalk (which is normally permeable) so a river could flow over the concordant coastline.
- The river erodes a valley on the frozen rocks
- During the inter glacial period the climate warms and sea levels rise. The sea uses the river valley to enter the coast line.
- The sea erodes the rocks, particularly the less resistant ones like Wealden Beds and Green Sands
- The erosion continues and the cove grows
- Finally there is a fully mature cove, wide in the middle (because of the less resistant rock there), narrow at the neck (the purbeck and portland limestone is more resistant to erosion) and elliptical (the chalk is also quite resistant to erosion)