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A tsunami was believed to have hit Britain in the 11th century causing destruction.
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-metre (9.8ft) tsunami that struck the coast of Cornwall with "great loss of life and property" according to 19th-century French writer Arnold Boscowitz.

Dr Teasdale, who spoke about his theory at the British Science Festival in Brighton, pointed out that since water covers 70% of the Earth's surface, asteroids were more likely to strike the ocean than land.

An excerpt from the Anglo Saxon Chronicles dated 1014 reads: "This year, on the eve of St Michael's day, came the great sea-flood, which spread wide over this land, and ran so far up as it never did before, overwhelming many towns and an innumerable multitude of people."

Twelfth-century English historian William of Malmesbury also talks of the catastrophe, describing a "tidal wave" of "astonishing size such as the memory of man cannot parallel, so as to submerge villages many miles inland and overwhelm and drown their inhabitants".