The rise and fall of global sea levels exposed and submerged the bridging land mass called "Beringia" several times in the Pleistocene. The Beringian land bridge is believed to have existed in the glaciation that occurred before 35,000 BP. During the more recent period 22,000-7,000 years BP it was also above water. The strait reopened about 15,500 BP and by c. 6000 BP the coastlines had their present form.