HALF a million years ago, Britain was connected to mainland Europe by a broad chalk ridge across what is now the Dover strait. Somehow that ridge was then destroyed, creating the English Channel. Now we know what destroyed it: a megaflood.
Sanjeev Gupta and Jenny Collier at Imperial College London came to this conclusion after studying images from an ultra-high-resolution sonar survey of the channel’s bedrock by the UK Hydrographic Office. This showed deep valleys that could only have been gouged out by vast volumes of water. “All the bedrock landforms we see are characteristic of a megaflood,” says Gupta.…
