A story of Doggerland, or when did exactly the British Isles separated from the continental Europe

Doggerland was an area now beneath the southern North Sea that connected Great Britain to continental Europe during and after the last glacial period. It was flooded by rising sea levels around 6,500–6,200 BC. 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.

Possible extent of Doggerland

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.

Map showing hypothetical extent of Doggerland 

Until the middle Pleistocene, Britain was a peninsula of Europe, connected by the massive chalk Weald–Artois Anticline across the Straits of Dover. During the Anglian glaciation, an ice sheet filled much of the North Sea, 

As ice melted at the end of the last glacial period of the current ice age, sea levels rose and the land began to tilt as the huge weight of ice lessened. Doggerland eventually became submerged, cutting off what was previously the British peninsula from the European mainland by around 6500 BC. The Dogger Bank, an upland area of Doggerland, remained an island until at least 5000 BC. Key stages are now believed to have included the gradual evolution of a large tidal bay between eastern England and Dogger Bank by 9000 BC and a rapid sea-level rise thereafter, leading to Dogger Bank becoming an island and Great Britain becoming physically disconnected from the continent.

A recent hypothesis postulates that much of the remaining coastal land was flooded by a megatsunami around 6200 BC, caused by a submarine landslide off the coast of Norway known as the Storegga Slide.

Map of the present-day coastline with Storegga Slide and height of the tsunami waves it created marked

Another view speculates that the Storegga tsunami devastated Doggerland but then ebbed back into the sea, and that later Lake Agassiz (in North America) burst releasing so much fresh water that sea levels over about two years rose to flood much of Doggerland and make Britain an island.

Lake Agassiz was a very large glacial lake located in the middle of the northern part of North America. Fed by glacial meltwater at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined.

Inhabitants

Mesolithic people populated Doggerland. Archaeologists and anthropologists say the Doggerlanders were hunter-gatherers who migrated with the seasons, fishing, hunting, and gathering food such as hazelnuts and berries. Evidence of Doggerlanders’ nomadic presence can be found embedded in the seafloor, where modern fishermen often find ancient bones and tools that date to about 9,000 years ago. These artifacts brought Doggerland’s submerged history to the attention of British and Dutch archaeologists and paleontologists.

A skull fragment of a Neanderthal, dated at over 40,000 years old, was recovered from material dredged from the Middeldiep, some 16 kilometres off the coast of Zeeland.

Woolly mammoth skull discovered by fishermen; Mammoth were one of the food sources of prehistoric "Doggerlanders"