A discordant coastline occurs where bands of different rock types run perpendicular to the coast. 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 A promontory is a raised mass of land that projects into a lowland or a body of water (in which case it is a peninsula). Most promontories either are formed from a hard ridge of rock that has resisted the erosive forces that have removed the so ...

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 Swanage () is a coastal town and civil parish in the south east of Dorset, England. It is at the eastern end of the Isle of Purbeck and one of its two towns, approximately south of Poole and east of Dorchester. In the 2011 census the civil ...

where the rock type is a softer greensand. North of

, the chalk outcrop creates the headland which includes Old Harry Rocks. The converse of a discordant coastline is a concordant coastline.

Examples

*The coastline around Durlston Bay () is an example of a discordant coastline.

Examples

See also