Antarctica: A Continent of Extremes
Antarctica is on average the coldest, driest, windiest, and highest continent on Earth. Covered by ice 2,000 meters (6,500 ft) thick, this continent is mostly uninhabitable.
Two Landmasses
Antarctica is really two distinct landmasses. East Antarctica is a "shield" — a dome of very ancient rocks within a continent. Geologically younger West Antarctica was formed in part by the same mountain-building processes that created the Andes.
High Peaks & Deep Valleys
Fifty years ago, scientists were stunned to discover a mountain range, the Gamburtsevs, completely buried under the ice. Now, new imaging has also revealed deep valleys, in a landscape some compare to the European Alps.
High Plateau
Composed entirely of ice, the Polar Plateau (now properly called the East Antarctic Ice Sheet) is the world's largest ice sheet. It sits 4,000 meters (13,000 ft) above sea level and covers most of East Antarctica.
Under-Ice Lakes
An interconnected network of lakes, large and small, is being discovered under the polar ice sheet. The largest of these lakes, Lake Vostok has been sealed under ice for millions of years. Scientists want to sample this environment but worry about contamination.
Katabatic Winds
Ferocious katabatic winds occur when dense, frigid air builds up on the high plateau. The air spills over, gathering speed like an "avalanche" as it tumbles toward the coast.
Sea Ice
Every fall and winter, the amount of sunlight falling on Antarctica decreases. As the surrounding ocean chills, it develops a coating of sea ice. In spring, as the Sun returns, the sea ice begins to retreat.
Powerful Current
The ocean current circling Antarctica is the most powerful current on the planet. Driven by strong winds from the west, this swirling moat of cold water stretches more than 20,000 kilometers (12,400 mi) around the continent and has isolated it for about 30 million years.
Ice Shelves
An ice shelf is a thick, floating mass of ice that forms as the ice sheet flows outward under its own weight. The shelves dam the flow of glaciers to the sea. As global temperatures rise, ice shelves on the Antarctic Peninsula seem to be collapsing more often, and more quickly, than in the past. Their loss may speed sea-level rise.
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