Discordant coastline

On a discordant coastline, rock bands run at right angles to the shoreline, exposing different rocks to the sea. Softer bands retreat faster, forming bays, while harder bands remain projecting as headlands. At Swanage Bay in Dorset, the bay lies in softer clay and sand, while nearby Ballard Point is formed from more resistant chalk.

On a discordant coastline, bands of rock meet the coastline at an angle, often approximately at right angles. Where alternating bands of harder and softer rock are exposed to the sea, they retreat at different rates. This is called differential erosion.

A bay is an inlet where the coastline curves inland. They can form where alternating bands of more resistant and less resistant rock meet the shoreline at roughly right angles. This arrangement is called a discordant coastline.