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The Atlantis of northern Europe sank under the seas slowly, rather than being obliterated by a tsunami. A little over 8000 years ago, a devastating tsunami swept across the North Sea, striking a small island that existed there at the time. But new evidence suggests the wave didn’t permanently swamp Dogger Island and its surrounding archipelago. People may have lived on the remaining land for centuries afterwards.
Between 110,000 and 12,000 years ago, Earth was in the grip of a glacial period – sometimes rather misleadingly called the last ice age. Because so much water was locked up in ice at the poles, sea levels were many metres lower. This means land that is now underwater was exposed.
This includes much of what is now the southern North Sea, between Britain and mainland Europe. As a result, Britain was connected to Europe by a fertile plain called Doggerland.
What happened to it? We know much of the polar ice melted, causing sea levels to rise around the world. By about 8200 years ago, Doggerland had gradually shrunk in size, leaving Dogger Island surrounded by a small archipelago (see image, above left). There is some evidence that this final piece of Doggerland had a dramatic end.
About 8150 years ago, a submarine landslide occurred off the coast of Norway, dubbed the Storegga Slide. This created a tsunami in the North Sea that hit the surrounding coastlines – in many areas, the wave was many metres deep. Many researchers have argued that the Storegga tsunami helped cut Britain off from Europe.
The issue is that so far, we have had no archaeological records of the tsunami’s impact on Doggerland. “We know essentially nothing about the actual impact on the areas which were patently most susceptible to be hit,” says Vince Gaffney at the University of Bradford in the UK.
As part of a long-term project to map Doggerland, Gaffney’s team took sediment cores from the seabed off the coast of East Anglia, in the east of England. The cores contain traces of the Storegga tsunami, such as broken shells. It seems the tsunami slammed up a river valley, ripping trees from the sides – and leaving their DNA in the sediments for the team to find. But the water soon retreated and later sediments suggest the area was above water again.
Gaffney’s team compiled existing data from around the North Sea. The researchers argue this suggests the Dogger archipelago survived for several more centuries. By 7000 years ago, it was underwater and had become what is now Dogger Bank: a submarine sand bank.
Simply obtaining the sediment cores was “a major undertaking”, says Karen Wicks at the University of Reading in the UK.
“It kind of confirms things we’d been thinking anyway,” says Sue Dawson at the University of Dundee in the UK.
Simulations of the tsunami had suggested it couldn’t have swamped Doggerland, and in some places, such as northern Norway, the wave may have been fairly small. The crucial factor is the exact shape of the coastline and nearby seabed, which affects how high the water rises, says Dawson.
Wicks has previously found evidence that the hunter-gatherer population in north-east Britain fell around the time of the tsunami. She argues that the tsunami was part of a “perfect storm” of environmental crises in the region, as it combined with a period of climate cooling 8200 years ago.
However, almost nothing is known about the people living on Doggerland. Last year, Gaffney’s team recovered the first known artefacts: two small pieces of flint. As a result, it is unclear how long people continued living there as the area slipped beneath the sea.
