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Heading South! (OLD REPORT - November 2002)

Deserts. When I think of such arid zones, I imagine shifting sands, prickly cacti, and intense heat, the kind that seems to suck all the water from your body in sweat as if trying to make you a desert too.

But one of the driest places on earth has temperatures that plummet to minus 50 degrees Fahrenheit - no wind chill factor. Glaciers protrude into the region creating walls of ice that are as high as 10 stories. The paltry 10 cm of water the region does get each year on average falls as snow. No cacti and essentially no other terrestrial vegetation for that matter, are anywhere to be found.

The valleys that make up this desert, which is among the coldest on earth, are collectively known as the McMurdo Dry Valleys, and they are located on the planet's southernmost continent, Antarctica.

The Dry Valleys

Only on a continent like Antarctica - 98 to 99 percent of whose surface is covered with ice - would such a barren place be referred to as an oasis. But with an area approximately one and a half times the size of Rhode Island, the Dry Valleys form the largest ice-free zone that the continent has, and as such, are a refuge of bare rock and soil.


The towering peaks of the Transantarctic Mountain Range prevent the Eastern Antarctic ice sheet from pushing into the Dry Valleys while the Wilson Piedmont Glacier helps keep moisture from nearby McMurdo Sound out. Cold air, such as that found in Antarctica, cannot hold as much water vapor as warmer air to start out with, and when winds push the air over mountains, it rises and cools even further. As this happens, the moisture the air does contain drops out. By the time it reaches the other side it's dry and the area downwind of the mountain is said to be in a precipitation shadow.


"The only deserts are
those of imagination"

Paolo Lugari,
founder of Gaviotas,
a sustainable community in Colombia

Strangely though, at the same time the Dry Valleys are incredibly dry, when compared with the rest of the frozen continent, the valleys are also remarkably wet. During the southern hemisphere's summer, which occurs during the northern hemisphere's winter, temperatures rise enough for glacial melting to occur. The meltwater forms streams that empty into some of the only lakes in the world with a permanent cover of ice