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Discordant coastline

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Durlston Head (limestone) to Handfast Point (chalk), with Peveril Point (limestone) dividing Durlston Bay from Swanage Bay

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.

References

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  1. ^ "Landform change – the Dorset coastline - Coastal landscapes – WJEC - GCSE Geography Revision - WJEC - BBC Bitesize". www.bbc.co.uk.

Examples

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See also

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