 During the most recent glaciation of the Last Glacial Maximum, which ended around 18,000 years ago, the North Sea and much of the British Isles were covered with glacial ice and the sea level was about lower.The climate later became warmer and during the Late Glacial Maximum around 12,000 BC Britain, as well as much of the North Sea and English Channel, was an expanse of low-lying tundra.Evidence, including the contours of the present seabed, indicates that after the first main Ice Age, the watershed between the North Sea and English Channel extended east from East Anglia then south-east to the Hook of Holland, rather than across the Strait of Dover.