Doggerland

Disappearance

It is generally thought that as sea levels gradually rose after the end of the last glacial period of the current ice age, Doggerland became submerged beneath the North Sea, cutting off what was previously the British peninsula from the European mainland by around 6500BC.[4] The Dogger Bank, which had been an upland area of Doggerland, is believed to have remained as an island until at least 5000BC.[4]

A more recent hypothesis is that much of the land was inundated by a tsunami around 8200BP (6200BC), caused by a submarine landslide off the coast of Norway known as the Storegga Slide. This theory suggests "that the Storegga Slide tsunami would have had a catastrophic impact on the contemporary coastal Mesolithic population... Following the Storegga Slide tsunami, it appears, Britain finally became separated from the continent and, in cultural terms, the Mesolithic there goes its own way."[6]