Tony Huerstel, age 12, of Tucson, Ariz., for his question:
HOW THICK IS THE SOUTH POLAR ICECAP?
If you walk at a brisk pace, in 20 minutes you can travel about one mile. And one mile is the average thickness of the South Polar icecap. In some places it is much thicker and in others it dwindles to almost nothing. And this enormous field of hard, frozen snow covers an area of 5 million square miles. on a shivering December morn, with the thermostat set stylishly low, it’s nice to know that things could be a lot worse. We could, for example, find ourselves marooned in June on the antarctic ice. There the midwinter temperatures are between minus 40 and minus 100 degrees. That is, if we avoid a spot called Vostok Station, where in August, 1960, the temperature plummeted to a shuddering minus 126.9 degrees.
The thickness of the ice would depend on where we happened to be, and the uneven South Polar icecap is large enough to cover the United States plus a sizable part of Canada. It humps up in the center, like a generous frosting on a planet size birthday cake. There are frosted mountain ranges, with a few blustery bare slopes. Some of the land below the ice is high plateaus, some is crushed down below sea level.
Ice is a fragile mineral that moves under its own weight. The South Polar cap pushes outward from at least two extra thick, dense areas in the interior. Directions are somewhat bewildering since every step from the South Pole must be northward. However, geologists refer to the region facing the Indian Ocean as East Antarctica and the region facing the Pacific is West Antarctica.
The South Pole, believe it or not, is in East Antarctica—and its ice is not the thickest. It is buried below a mere 9,000 feet of frozen snows. In the western region, the great icecap blankets lofty ranges and vast plateaus under 12,000 feet or more. In one region it crushes the plateau far below sea level—and tops it with a layer of ice 14,000 feet thick. There may be thicker ice in other parts of Antarctica, though so far they have not been measured.
Ice from the central hump pushes outward sometimes as fast as 2,500 feet a year. The edges of the stupendous snowfield face the sea with cliffs of ice, 1,000 feet high. They stand 150 feet above the chilly waves, and another 850 feet are submerged below the water.