Discordant coastline
![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/13/Durlston_bay_from_durlston_castle.jpg/250px-Durlston_bay_from_durlston_castle.jpg)
A discordant coastline occurs where bands of different rock types run perpendicular to the coast.[1]
The differing resistance to erosion leads to the formation of headlands and bays. A hard rock type such as granite is resistant to erosion and creates a promontory whilst a softer rock type such as the clays of Bagshot Beds is easily eroded creating a bay.
Part of the Dorset coastline running north from the Portland limestone of Durlston Head is a clear example of a discordant coastline. The Portland limestone is resistant to erosion; then to the north there is a bay at Swanage where the rock type is a softer greensand. North of Swanage, the chalk outcrop creates the headland which includes Old Harry Rocks.
The converse of a discordant coastline is a concordant coastline.
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.