Antarctica

Without its icy cover, much of west Antarctica would lie beneath sea level, partly because the ice has weighed down the continent. If, when Earth's climate was warmer, Antarctica lost significant quantities of ice, areas of the ice sheet may have become thin and buoyant enough to float above the rocky continent. Seawater would then have flooded beneath the ice and created narrow channels across the continent between chunks of rock that retained their icy caps.

http://tinyurl.com/6qvwprn

Via Dr. Stefan Gruenwald