SALT + EARTH Festival: Sanjeev Gupta - Megaflood

When engineers digging the Channel Tunnel finally hacked through the chalk and shook hands in December 1990, it was the first time Britain and mainland Europe had been linked for hundreds of millennia. Now we know what separated those land masses in the first place: a megaflood.

Half a million years ago, Britain was connected to mainland Europe by a broad chalk ridge that spanned what we now call the Dover Strait. But somehow that ridge was destroyed, forever separating England and France. All that is left visible of the chalky ridge on the British side are the White Cliffs of Dover.

Sanjeev Gupta and Jenny Collier from Imperial College London together with French and Belgian scientists have discovered remarkable evidence that a huge megaflood or series of megafloods was responsible. They analysed a hidden series of massive valleys on the floor of the English Channel – vast gouges in bedrock 50 metres deep and tens of kilometres wide.

These valleys were first noticed by geologists in the 1970s studying routes for the Channel Tunnel beneath the Dover Strait but until now, no one really knew what caused them. The international research team decided to find out with the help of modern technology. They used high-resolution geophysical data to create maps of The Channel floor and subsurface and found that this hidden world was remarkably well preserved.

Sanjeev will give an illustrated talk on the megaflood and will then be joined for an in-conversation with Melanie Wrigley from White Cliffs Countryside Partnership.

Sanjeev Gupta is interested in the processes that shape landscapes and how they evolve through time. He is a professor of Earth Sciences at Imperial College London and his work has encompassed not only the submerged landscapes of the English Channel, but also the landscape of early Bronze-age civilisations.

His current work jumps between working with NASA rovers on Mars searching for evidence of ancient life, and studying water resources and environments of densely populated river landscapes in India.

He contributed to the BBC Radio 4 series The Channel (Series 1) From Landscape to Seascape and the BBC Radio 3 programme Private Passions.