The North Sea Used to Be a Country, and a Tsunami Drowned the Last of It

If you could lower the North Sea by about 60 meters today, you would expose a country. Around 23,000 square kilometers of dry land — a region archaeologists call Doggerland — sat between what is now Norfolk and the Netherlands at the end of the last Ice Age. It had river valleys, salt marshes, and a population of Mesolithic hunter-gatherers walking after deer and aurochs.

The direct evidence comes mostly from fishing nets. In 1931, the trawler Colinda hauled a peat block out of waters off the Norfolk coast and split it open onshore; embedded inside was a barbed antler harpoon point about 8.5 inches long, dated by later analysis to between 10,000 and 4,000 BCE. Since then, North Sea trawlers have routinely brought up mammoth tusks, cave-lion bones, flint tools, and at least one Neanderthal skull fragment over 40,000 years old, exhibited in Leiden in 2009. None of this is from a sunken city. It is the bottom of an old landscape.

The water arrived in two stages. Sea level rose enough to make Britain a peninsula, then an island, by roughly 6500 BCE. Around 6200 BCE, an enormous submarine landslide off the Norwegian coast — the Storegga Slide — sent a tsunami across the remaining lowland. Estimates of casualties on the British coast vary wildly, but several researchers think a quarter of the Mesolithic population of Britain may have died. The Dogger Bank persisted as an island for another thousand years before slipping under as well.