Was Britain's west coast hit by a devastating tsunami caused by an 11th Century asteroid strike?

An asteroid impact in the Atlantic in the 11th century may have caused a huge tsunami that swept across the west coast of Britain, scientists believe.

While there are doubts over whether the devastating event actually took place, the disaster is said to have submerged large numbers of villages and was mentioned in 1014 AD in the Anglo Saxon Chronicles.

And researchers say they have now found likely tsunami deposits at Marazion Marsh in Cornwall and Dorset’s Chesil Beach from roughly the same time period, suggesting the story may be more than a legend.

Discovery – Chesil Beach, where researchers say they have found likely tsunami deposits (Pictures: Getty)

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.”

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Tsunamis 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.

Discovery – deposits were also found at Marazion Marsh in Cornwall

Dr Teasdale, who spoke about his theory at the British Science Festival in Brighton, said since water covers 70% of the Earth’s surface, asteroids were more likely to strike 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”.