THE CONTINENT

Antarctica occupies about 9% of the earth's total land surface. For this to be true, of course, you must accept snow and ice as “land surface,” because this is what mainly constitutes that part of the continent that lies above sea level. Think of the antarctic continent as a vast convex lens of ice with a thin veneer of snow. In contrast to the region around the north pole, which is just floating ice at the surface of the ocean, the antarctic ice lens rests on solid rock. In most places the ice is so thick, and weighs so much, that it has depressed the underlying rock to about sea level. If the ice melted completely, the surface of the continent would rebound over a long period of time until its average elevation would be higher than any other continent. As it is, the ice surface itself gives Antarctica a higher average elevation than any other continent.

It is only in a very few places, where mountains defy the ice cover, that we can directly sample the underlying rocks. Most of these places are near the coast, where the ice sheet thins. At the center of the continent the elevation is about 4000 m. At the south geographic pole, which is not at the center of the continent, the elevation is 3000 m.