Post by Watchman on Jul 20, 2007 11:09:58 GMT -5
STEPHEN MCGINTY
A FLOOD of Biblical proportions swept away the hills which once joined England to France and created the British Isles, according to explosive new research which reshapes the geological history of Britain.
While it had previously been thought that the English Channel was formed by slow erosion combined with rising sea levels, academics now believe it was created in weeks or months as a result of a cataclysmic flood which took place between 200,000 and 450,000 years ago.
If they are correct, Neanderthal man in what is now Dover would have gazed out at a 400ft-high waterfall the size of Niagara, which poured out one million cubic metres of water per second.
The water, which came from what is now the North Sea, but was then a lake that sat hundreds of feet above the Strait of Dover, punched through the soft chalk hills uniting England and France and flowed into the Atlantic.
Chris Stringer, head of human origins at the Natural History Museum in London and one of the authors of a paper published yesterday in Nature magazine, said: "This could have been one of the most powerful flood events ever known on Earth."
The dramatic discovery emerged from highly detailed underwater sound-waves that captured spectacular images of the seabed of the Channel a few miles off the Sussex coast. The equipment is able to see through thick layers of sediment to the seabed beneath. Team members were surprised to find the remains of a huge valley, partly hidden by accumulated mud, running south-west from the Strait of Dover.
The researchers also discovered huge scour marks, deep bowls and piles of rock that could only have been created by a giant torrent of water - triggering an important revision of the understanding of prehistoric Britain.
The study is part of the "Ancient Human Occupation of Britain" project and shows a huge valley more than seven miles wide and up to 170ft deep carved into chalk bedrock on the floor of the English Channel.
Dr Sanjeev Gupta, of Imperial College London, the leader of the study, said: "In places, this huge underwater valley is more than seven miles wide and 170ft deep, with vertical sides.
"Its nearest geological parallels are found not on Earth, but in the monumental flood terrains of the planet Mars.
"This suggests that the valley was created by catastrophic flood-flows following the breaching of the Dover Strait and the sudden release of water from a giant lake to the north."
He added: "This 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 120,000 years."