The Channel is of geologically recent origins, having been dry land for most of the Pleistocene period. It is thought to have been created between 450,000 and 180,000 years ago by two catastrophic glacial lake outburst floods caused by the breaching of the Weald-Artois Anticline, a ridge which held back a large proglacial lake in the Doggerland region, now submerged under the North Sea. The flood would have lasted several months, releasing as much as one million cubic metres of water per second. The cause of the breach is not known but may have been caused by an earthquake or simply the build-up of water pressure in the lake. As well as destroying the isthmus that connected Britain to continental Europe, the flood carved a large bedrock-floored valley down the length of the English Channel, leaving behind streamlined islands and longitudinal erosional grooves characteristic of catastrophic megaflood events.[4]
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