Sea level swings by 120 metres
Every glacial cycle drains and refloods the continental shelves, opening and closing land bridges.
- When
- —
- Duration
- 645 thousand years
- Known to
- ± 30 thousand years
- Era
- Middle Pleistocene, Quaternary
Locking up enough water to build kilometre-thick ice sheets lowers global sea level by up to 120 metres, exposing continental shelves worldwide: Beringia, the North Sea plain, the Sunda and Sahul shelves. Each fall creates land bridges and each rise drowns them, repeatedly connecting and isolating populations of animals and, later, people. Much of the archaeological record of coastal life for this entire period is now underwater.