Thursday, November 16, 2006

Lulworth Cove and Stair Hole

The coast around Lulworth Cove demonstates all stages in the development of bays and headlands, and how that development is controlled by the underlying geology. Along this section of the coast, the rocks have been tilted into a near vertical position

The oldest rocks, Portland Limestone, provides a barrier to the sea, behind which are progressively softer rocks, Purbeck Limestone, Lower Greensand, Wealdon Clay and Upper Greensand. The youngest rocks are chalk, which although soft are massive in thickness

The river that runs into the cove at one time reached the sea, through a cut in the hard Portland Limestone barrier. This allowed the sea to erode the Limestone. Once the sea reached the softer rocks behind, especially the Wealdon Clay, rapid erosion took place. Once the sea reched the 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 form one larger cove

Source: text

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