The first Brexit happened thousands of years before the United Kingdom voted to politically leave the European Union and this happened when Britain geologically broke off from the rest of Europe.
Brexit 1.0
Ancient Britain's separation from the rest of Europe occurred in a two-stage flooding event that destroyed the thin strip of land that used to connect it to France.
Researchers called this "Brexit 1.0."
Researchers said that a large lake likely overflowed 450,000 years ago, about the same time when the Neanderthals are believed to have first appeared in Europe. The second event, which happened 160,000 years ago involved a catastrophic flood that opened the Dover Strait in the English Channel, which now separates Britain from the rest of Europe.
Events That Severed The Geological Link Between Britain And Europe
Reporting in a study published in the journal Nature Communication on Tuesday, researchers said that they have now found evidence that could explain how the opening of the Dover Strait that severed the land between Britain and France happened.
Study researcher Jenny Collier, from Imperial College London, said that evidence suggests that 450,000 years ago, Dover Strait may have been a huge rock ridge of chalk that looked more like Siberia's frozen tundra than the green environment it is today.
"It would have been a cold world dotted with waterfalls plunging over the iconic white chalk escarpment that we see today in the White Cliffs of Dover," Collier said.
About 10 years ago, researchers found geophysical proof of giant valleys on the seafloor in the English Channel, which they thought were evidence of a large flood gouging out of the land that may have been caused by a breach in the chalk rock ridge that once joined Britain to France.
Now geophysical data from France and Belgium and seafloor data from Britain showed huge holes and valley system on the seafloor helping researchers establish how this breach of the chalk ridge occurred.
The ridge served as a huge dam with a proglacial lake behind it. Once the lake overflowed, its waters started to cascade like waterfalls over the Dover-Calais land bridge. Laden with abrasive flints that were dissolved from the chalk, the waterfall caused holes in the bedrock beneath eroding and weakening the land bridge.
A section then gave way. In a cataclysmic flood, huge amounts of water were eventually released as the glacial lake poured itself into the English Channel.
"Sub-bottom records reveal a remarkable set of sediment-infilled depressions that are deeply incised into bedrock that we interpret as giant plunge pools. These support a model of initial erosion of the Dover Strait by lake overspill, plunge pool erosion by waterfalls and subsequent dam breaching," researchers wrote in their study.
How Ancient Proglacial Lake Split Over
Collier and colleagues said it is not yet clear how the proglacial lake split over but they have theories.
"Perhaps part of the ice sheet broke off, collapsing into the lake, causing a surge that carved a path for the water to cascade off the chalk ridge," Collier said adding that an earthquake may have contributed to more weakening of the ridge causing it to collapse.
