A devastating tsunami caused by an asteroid impact in the Atlantic may have swept across the west coast of Britain in the 11th century, scientists believe. The disaster is said to have submerged large numbers of villages and was mentioned in 1014 AD in the Anglo Saxon Chronicles, but there are doubts over whether the event really occurred. Researchers say they have now found likely tsunami deposits at Marazion Marsh, Cornwall, and Chesil Beach, Dorset, from roughly the same time period that suggest the story is more than a legend. Geographer Dr Phill Teasdale, from the University of Brighton, said: "If we can investigate this a bit more, we can talk about the geographical spread of the impact. "Analysing the depth of the tsunami deposit can tell us whether that postulated asteroid impact in the Atlantic ocean was a reality." Tsunamis are destructive fast-moving waves that can be triggered by earthquakes, mountain slides, or meteor impacts. In 1755 the Lisbon earthquake caused a three