sentences:  Around 10,000 years ago, during the Devensian glaciation with its lower sea level, Great Britain was not an island, but an upland region of continental northwestern Europe, lying partially underneath the Eurasian ice sheet.The sea level was about lower than today, and the bed of the North Sea was dry and acted as a land bridge, now known as Doggerland, to the Continent.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 6500 BC.