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Saturday, April 08, 2017

Evidence of ancient 'geological Brexit' revealed.

By Rebecca Morelle

Science Correspondent, BBC News

4th April 2017

The UK has now started the formal process of leaving the EU, but scientists say they have evidence of a much earlier "Brexit". They have worked out how a thin strip of land that once connected ancient Britain to Europe was destroyed. The researchers believe a large lake overflowed 450,000 years ago, damaging the land link, then a later flood fully opened the Dover Strait. The scars of these events can be found on the seabed of the English Channel. The study is published in the journal Nature Communications. Professor Sanjeev Gupta, who led the study, from Imperial College London, said: "This was really one of the defining events for North West Europe - and certainly the defining event in Britain's history. This chance geological event, if it hadn't happened, would have meant Britain was always connected to the continent."

More than half a million years ago, in the midst of an Ice Age, a land bridge connected Dover in the South of England to Calais in northern France. Immediately to the north of it, was a huge glacial lake, which had formed at the edge of an ice sheet that covered much of Europe. The researchers believe that this lake started to overflow, sending vast amounts of water crashing over the land bridge. The evidence for this was found at the bottom of the English Channel. Decades ago, engineers who were surveying the seabed for the Channel Tunnel, discovered a series of mysterious large underwater holes. Now further scrutiny has revealed that they were most likely caused by the lake overspill. Prof Gupta said: "These holes are now in-filled with sediment, but what's interesting is that they are not linear features like canyons or valleys - they are isolated depressions. And they occur in a line - a whole series of them stretching between Dover and Calais. And they are huge, 100m-deep carved into the bedrock and hundreds of metres to several kilometres in diameter. So we interpret these as giant plunge pools. We think there was basically lake water plunging over this rock ridge in the Dover Strait through a whole series of waterfalls, which then eroded and carved out these depressions. It's difficult to explain them by any other mechanism."

The researchers believe the lake started to overflow about 450,000 years ago, which would have seriously weakened the land bridge. But they think a second catastrophic flood that took place about 150,000 years ago would have destroyed it altogether. "We see this huge valley carved through the strait, about eight to 10km wide... and it has a lot of features that are suggestive of flood erosion," said Prof Gupta. Co-author Jenny Collier, also from Imperial College London, said it was not clear what caused either of these events. She said: "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. In terms of the catastrophic failure of the ridge, maybe an earth tremor, which is still characteristic of this region today, further weakened the ridge. This may have caused the chalk ridge to collapse, releasing the megaflood that we have found evidence for in our studies." The researchers would now like to work out more precise timings of the "geological Brexit". This would mean drilling into the bottom of the Dover Strait and analysing the age of the sediment. "But that would be a huge undertaking," admitted Prof Gupta. "The English Channel is the world's busiest shipping lane and it has huge tidal currents. It will be hugely challenging."

[Imagine how different European, and probably World, history would have been if the land bridge to the Continent had not been washed away all that time ago. What would have stopped Napoleon from marching across France and into England? Could the British army have stopped him? Probably, but could we have stopped Hitler in 1940? I doubt that very much. After Dunkirk the Channel protected us from imminent invasion. Without it? Well, just say that the world would be a very different place with a very different past! I might very well be speculating about how different things would have been if the land bridge had been washed away – except I’d be typing this in German. Interesting to speculate isn’t it?]


Mudpuddle said...

very interesting article... my training was in geology although i don't do it much now, being retired... but i know that the ice age caused a lot of damage... another example is the Columbia River gorge, caused by the sudden failure of an ice dam that allowed enough water to cover the state of Washington three feet deep to wash down through the river all at once... it eroded out the river bed and covered the willamette valley, creating present-day surface features and also formed a huge lake eastward of the Dalles...

don't mess with mother nature!!

CyberKitten said...

I have dabbled a bit in Geology - reading about it anyway - although Biology and especially Evolution are more my thing. I have an interest in Quantum Mechanics too though I don't understand it very well.

Nature isn't to be messed with I agree. It's a pity then that's exactly what we are doing. We'll learn (possibly) one day, maybe.... [grin]

Stephen said...

With a land bridge in place, history would have evolved very differently..so differently, in fact, that Hitler and Napoleon might not have even existed. Perhaps a great Celtic Empire would have emerged...

CyberKitten said...

Quite possibly Stephen. Imagine a Franco-English-German Celtic army defeating the Romans and then taking over their Empire?

Stephen said...

Well, if Britain were still united to the Continent I could certainly some see some sort of Celtic state forming up there in response to the Roman exploration of Gaul. This is all speculation, but if the Britons truly supported the Gauls against the Roman invasion in real life (which is why Caesar investigated Britain to begin with, allegedly), then they might support one another more effectively without the Channel in the way. (Of course, if Rome had met that kind of opposition in the west, against a more solid Celtic nation AND the Germans, it might have never tried to expand into Persia's domain....this is the problem and the fun of alt-history, there's so many things whirling around affecting other things!)

By the way, I was just playing a game of Civilization III which might amuse you. Playing a map of Europe where the start locations are random, I began as ROME on the Thames, and as I do pushed the research of boats so I could land a settler on the Continent. Imagine my surprise to find the English in Gaul. I have therefore invaded England in Gaul as Rome. Having conquered them, I'm now divided between settling a mysteriously-vacant Iberia, or attacking those Egyptians in Italy. Most confusing. I took a screenshot but can't find it at the moment. I'll keep looking for it!

CyberKitten said...

Alt-History is FUN and very, very complex if you're doing it right!

LOL with Civ III. That must be really messing with your head!