Britain was once joined to Europe by a landmass now sunk beneath the North Sea

Doggerland was a broad plain linking Britain to continental Europe, exposed as ice sheets retreated around 18,000 years ago. As recently as 10,000 years ago, people could walk from what's now Yorkshire to Denmark. Rising seas gradually drowned it, and a tsunami from Norway's Storegga landslide around 6150 BCE helped finish the job.

— Vincent Gaffney, Simon Fitch, David Smith, Europe's Lost World: The Rediscovery of Doggerland — CBA Research Report 160, Council for British Archaeology, 2009
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