New research reveals that the first Brexit actually occurred thousands of years prior to the United Kingdom voting to exit from the European Union: It separated geologically from the rest of Europe.

But what makes the so-called “Brexit 1.0” an important piece of ancient history?

How It Likely Happened

The historic separation followed a two-phase flooding event that destroyed the thin connecting land between ancient Britain and France.

The first event involved a massive overflowing lake from about 450,000 years ago. The second event, on the other hand, occurred 160,000 years earlier, with a huge flood opening the Dover Strait in the English Channel, which now separates Britain from the rest of the continent.

According to new evidence, Dover Strait some 450,000 years earlier may have served as a huge rock ridge of chalk, with a huge dam boasting a proglacial lake behind it that resembled Siberia’s frozen tundra more closely than its modern green surroundings.

It initially eroded via lake overspill, followed by “plunge pool erosion by waterfalls and subsequent dam breaching,” researchers said in the journal Nature Communication.

What If Brexit 1.0 Didn’t Happen?

The researchers are convinced that Britain left Europe in earlier times through the catastrophic route than just simple erosion. The glacial lake, probably induced by an earthquake that weakened the ridge further, over-spilled staggering amounts of water.

"The waterfalls were so huge they left behind the plunge pools, some several kilometers in diameter and 100 meters [328 feet] deep in solid rock, running in a line from Calais to Dover," explained author Jenny Collier of Imperial College London.

Had the first flood not taken place, Britain could still be connected to Europe today. In that scenario, it could be jutting out the way Denmark does at present, the researchers added.

The next step for the team is to take samples from the plunge pools to obtain more data on the events’ timings. One major issue, however, is that the waters above the holes are now the site of one of the world’s busiest shipping lanes.

Significance Of Dover Strait

A shallow, narrow channel that spans less than 30 kilometers (18.6 miles), Dover Strait links the North Sea, English Channel, as well as the Atlantic.

The area has enormous strategic importance from the earliest waves of invasion and defense, with features such as the Martello Towers built during the Napoleonic War and the World War II frontline fortifications and anti-tank devices along the whole coast.

But beyond being of great historic interest, the strait also serves as a busy international shipping lane with more than 500 ship movements every day. In addition, it is a crucial spawning site for marine wildlife and a migration route that sees more than 250 bird species in any given year.

Dover Strait’s utmost significance simply lies in the two events that unfolded thousands of years ago.

“The opening of the Strait has significance for the biogeography and archaeology of NW Europe, with particular attention on the pattern of early human colonization of Britain,” the team wrote.