Old Harry Rocks

Old Harry Rocks are a set of chalk formations at Handfast Point on the Isle of Purbeck in Dorset, England, marking the easternmost point of the Jurassic Coast World Heritage Site. The chalk was deposited in the Late Cretaceous, roughly 84 to 72 million years ago, and contains bands of flint that resist erosion differently than the surrounding rock. Waves forced air and water into cracks in the cliff face, widening them into caves and then arches whose collapsed roofs left behind disconnected stacks; the formation once included a companion stack known as Old Harry's Wife, which fell in 1509. The National Trust, which manages the site, has chosen to let natural erosion continue rather than intervene, so new stacks are expected to emerge from the cliff as older ones weather away.