Geological evidence supports theory of surge down the English Channel.

The island that is now England, Scotland and Wales was severed from continental Europe by a cataclysmic flood during the last ice age, according to a group of researchers based in Britain.

The team, led by Sanjeev Gupta, a geologist at Imperial College London, have found strong evidence at the bottom of the English Channel for a ’super-flood’ theory first suggested more than 20 years ago.

… Hundreds of thousands of years ago, a ridge of chalk rock stretched from England to France, roughly between Dover and Calais. To the northeast of this ridge, melting ice and rivers fed a huge glacial lake, blocked in the north by a wall of ice, which was the primeval start of today’s North Sea. To the southwest, Britain was connected to Europe by low-lying land.

At some point, the rising waters of the North Sea lake must have over-topped the ridge, creating a massive waterfall down to the southwest. A first flood probably occurred around 425,000 years ago, the team proposes, as other evidence points to the existence of a North Sea lake at that time.

… A second spill is likely to have occurred some 200,000 years later, during the most recent ice age, when again ice would have blocked up the north and created a lake where today’s North Sea lies. This flood was probably even more powerful than the first one, enlarging the Dover Strait to almost its present size. From then on, Britain would have been an island, only intermittently connected to the continent during times of extremely low sea level.

[Quirin Schiermeier: Nature.com: 18 July 2007]