Seven Sisters, England

The Seven Sisters are a line of white chalk sea cliffs along the English Channel coast of East Sussex, England, part of the same Cretaceous Chalk Group as the White Cliffs of Dover, deposited from calcareous marine sediment roughly 100 to 66 million years ago and later uplifted above sea level. Their name comes from the undulating series of rounded peaks and troughs visible along the cliff line, which correspond to the mouths of dry valleys that once ran across the chalk downland; as the coastline has retreated under wave erosion, each valley has been truncated, leaving the high point between two neighboring valleys standing as one of the "sisters." The cliffs continue to retreat by roughly a third of a meter per year on average through ongoing coastal erosion.