Doggerland

Doggerland was an area now beneath the southern North Sea that connected Great Britain to continental Europe during and after the last Ice Age. It was flooded by rising sea levels around 6,500–6,200 BCE. Geological surveys have suggested that it stretched from Britain's east coast to the Netherlands and the western coasts of Germany and the peninsula of Jutland. It was probably a rich habitat with human habitation in the Mesolithic period, although rising sea levels gradually reduced it to low-lying islands before its final submergence, possibly following a tsunami caused by the Storegga Slide.

The archaeological potential of the area had first been identified in the early 20th century, but interest intensified in 1931 when a fishing trawler operating east of the Wash dragged up a barbed antler point that was subsequently dated to a time when the area was tundra. Vessels have dragged up remains of mammoth, lion and other animals, as well as a few prehistoric tools and weapons.

Doggerland was named after the Dogger Bank, which in turn was named after the 17th century Dutch fishing boats called doggers.

Until the middle , Britain was a peninsula of Europe, connected by the massive chalk Weald–Artois Anticline across the Straits of Dover. During the Anglian glaciation, approximately 450,000 years ago, an ice sheet filled much of the North Sea, with a large proglacial lake in the southern part fed by the Rhine, Scheldt and Thames river systems. The catastrophic overflow of this lake carved a channel through the anticline, leading to the formation of the Channel River, which carried the combined Scheldt and Thames to the Atlantic. This probably created the potential for Britain to become isolated from the continent during periods of high sea level, although some scientists argue that the final break did not occur until a second ice-dammed lake overflowed during the MIS8 or MIS6 glaciations, around 340,000 or 240,000 years ago.

...
Wikipedia