The Dry Valleys of Antarctica
The fact that Antarctica is the coldest continent surprises few people; the windiest, too, comes as no great shock. The title “Highest Continent” comes from the great bowl of ice that fills the interior to more than 13,000ft above sea level. But the driest continent? This is unexpected until one considers that Antarctica is a freezer, and freezers aren’t wet; they’re dry. It’s a polar icebox, a dehydrator, a crystal desert. Nowhere is the desiccating cold and timeless wind more acute than the Dry Valleys of the Admiralty Mountains of Victoria Land, across McMurdo Sound from Ross Island, which has been bare and arid for two million years. The Dry Valleys were discovered accidentally by Robert Falcon Scott and two companions in 1903. Low on food and fuel and pulling sledges as the British preferred, the threesome descended the wrong glacier in thick fog. Hoping to emerge at McMurdo Sound they instead found themselves on the edge of a frozen lake surrounded by polygonally patterned ground in a rocky ice-free valley. Equipped for sledging, not trekking, they had to retrace their steps. In doing so they avoided the fate of seals and penguins that had wandered into the Dry Valleys hundreds of years ago, some of them thousands of years ago, and found it a one-way trip. Their mummified remains lie amid wind-polished rocks, offering silent testimony to entombment in the changeless dry and cold. Not until 1946-47 did aerial photography reconnaissance reveal the full extent of the Dry Valleys at more than 1,200 square miles; the largest ice-free are on the continent. Smaller dry valleys exist in Antarctic Peninsula.
The Dry Valleys are in fact contrarian. There is no moisture in a desert, but an island of rock in a sea of ice, hardly more hospitable than their surroundings. Temperatures range from 15 degrees Celsius (59F) to -80 degrees Celsius (-112F). Evaporation exceeds precipitation. Windblown sands etch and polish fine-grained rocks, called ventifacts, into three-four-sided pyramids with intricately fluted faces. Course grained rocks crumble to the ground, crystal by crystal. No animals call or cry. Nothing moves, except the wind and what it carries. Unlike Mars (at least Mars as we know it), life does persist in the Dry Valleys, and in remarkably reclusive ways. Translucent, porous rocks (quartz, sandstone, some granites, and marbles) provide homes for cryptoendolithic communities of lichens, fungi, and algae that by tiny filaments and spores burrow into the surface cracks and interstices between crystals (only a few millimetres deep) to survive by the thinnest of margins. When the rock cleaves and falls to the ground, the organisms fall with it. Naked and exposed, they die. Spores on the wind play even greater odds, as maybe one in a million alights in a rocky crevice where it becomes a pioneer and a refugee; the others, like dust, blow to oblivion.
Image Credit: http://icestories.exploratorium.edu/dispatches/big-ideas/dry-valleys/ Further Reading: McMurdo Dry Valleys: http://www.mcmurdodryvalleys.aq/ The Dry Valleys: http://thedryvalleys.com/2009/12/13/ventifacts/ Antarctica’s Dry Valleys: http://discovermagazine.com/galleries/2013/june/dry-valleys-diary Antarctic Connection, The Dry Valleys: http://www.antarcticconnection.com/shopcontent.asp?type=science-dry-valleys Robert Falcon Scott: http://www.south-pole.com/p0000089.htm Horowitz, N. H., Cameron, R. E., & Hubbard, J. S. (1972). Microbiology of the dry valleys of Antarctica. Science, 176(4032), 242-245. José, R., Goebel, B. M., Friedmann, E. I., & Pace, N. R. (2003). Microbial diversity of cryptoendolithic communities from the McMurdo Dry Valleys, Antarctica. Applied and Environmental Microbiology, 69(7), 3858
