The Pinnacles on the Isle of Purbeck in Dorset, England

Welcome to the waters off the Isle of Purbeck in Dorset, a peninsula which extends out into the English Channel. These chalk headlands started forming tens of millions of years ago and are still not finished. The two chalk formations you can see in our homepage image are known as The Pinnacles. Thousands of years ago, these stacks would have been connected to others nearby. Many rock formations like these have come and gone in the meantime, and new ones are still forming as the sea finds weaknesses in the stone, forming arches which eventually collapse, creating new stacks.
© James Osmond/Alamy