Doggerland
From Tardis Wiki, the free Doctor Who reference
Doggerland was a land bridge which connected the British Isles to continental Europe during and prior to the Stone Age. On 7 September, 6200 BC, the exodus of Doggerland occurred, and Stone Age people fled Doggerland as it gradually fell into the sea. A guide for time travellers suggested possible Sea Devil involvement. (PROSE: Time Traveller's Diary)