The coast around Lulworth Cove demonstrates every stage in the development of bays and headlands and how that development is controlled by the underlying geology.

Lulworth Cove

Along this section of coast the rocks have been tilted into a near vertical position. The oldest rocks, the Portland Limestone, provide a barrier to the sea but behind it are progressively softer rocks, Purbeck Limestone, Lower Greensand, Walden Clay and Upper Greensand. The youngest rocks are the Chalk, which, although soft, is massive in thickness.

The Formation of Lulworth Cove

Stair HoleThe river that runs into the Cove at one time reached the sea through a cut in the hard Portland Limestone barrier. This breach allowed the sea to erode the limestone. Once the sea reached the softer rocks behind, especially the Wealden Clay, rapid erosion took place. Once the sea reached the massive Chalk, erosion slowed, forming the perfect bay. To the west, the sea has been eroding the Portland Limestone at Stair Hole and the process of bay formation has just begun. Eventually Lulworth Cove and Stair Hole will combine into one larger cove, rather like Man O' War Cove further along the coast.