'Megaflood started Britain's island heritage'
Sonar readings reveal English Channel scour marks
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Thursday, 19, Jul 2007 12:19
The UK owes its heritage as an island nation to a "catastrophic megaflood" that separated what is now mainland Britain from France hundreds of thousands of years ago.
New research based on sonar studies claims to have uncovered deep scour marks on the bed of the English Channel that indicate an immense discharge of water.
Scientists from the UK claim that an ice-dammed lake in what is now the North sea was behind the flooding.
Publishing their findings in the journal Nature, the Imperial College London researchers state that an unknown event, possibly an earthquake, which took place between 450,000 and 200,000 years ago, caused the lake to breach the Weald-Artois chalk ridge that spanned the Dover Straits.
This flood, described as one of the largest in history, is estimated to have lasted several months and seen more than one million cubic metres of water discharged every second.
Dr Sanjeev Gupta from Imperial's Earth science and engineering department says that the megaflood explains the sudden absence of humans in Britain 100,000 years ago.
"This prehistoric event rewrites the history of how the UK became an island and may explain why early human occupation of Britain came to an abrupt halt for almost 120 thousand years," she writes.
Her department colleague Jenny Collier added: "The preservation of the landscape on the floor of the English Channel, which is now 30 to 50m below sea-level, is far better than anyone would have expected.
"It opens the way to discover a host of processes that shaped the development of north-west Europe during the past million years or so."