the english channel is thought to have been created between 450,000 and 180,000 years ago by two catastrophic glacial lake outburst floods caused by the breaching of the weald-artois anticline, a ridge that held back a large proglacial lake, now submerged under the north sea. 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.