Description
Durdle Door on Dorset’s Jurassic coast is all that remains of a long rib of limestone that once ran parallel to the shore, a landform known as a concordant coastline. The horizontally laid down rocks have been folded upwards into a nearly vertical alignment by earth movements. Where a joint between these layers is weaker wave-action has opened up a sizeable archway. This location marks a boundary between Jurassic Portland Limestone and chalk from the subsequent Cretaceous period.
