At this plain 's greatest extent during the Last Glacial Maximum , sea level was 100 -- 120 m below modern sea level .
The coastline was located 700 to 1,000 kilometres ( 430 -- 620 miles ) north of its current position .
At this plain 's greatest extent during the Last Glacial Maximum , sea level was 100 -- 120 m below modern sea level and the coastline was located 700 to 1,000 kilometres ( 430 -- 620 miles ) north of its current position .