While 98% of Antarctica is covered in ice—some of it two miles deep—one area is a fascinating exception: the region called the Dry Valleys. This row of valleys, west of McMurdo Sound, contains the largest ice-free region in Antarctica. It is free of ice because the Transantarctic Mountains create a "rain shadow," allowing so little precipitation into the Dry Valleys that they comprise the driest desert system in the world. With an average temperature of -20ºC (-4.0ºF), scientists consider the cold, windy, and extremely dry environment of the Dry Valleys to share some similarities with the climate on the surface of Mars.

The Dry Valleys were first discovered in 1903 by explorer Robert Scott and his party, who referred to the region as the "Valley of the Dead." Griffith Taylor, Charles Wright, and Raymond Priestley of the British Antarctic Expedition (1910–1913) conducted the first scientific studies of the region in 1911, studying the formation and structure of surface features. Scientists returned to the Dry Valleys during the International Geophysical Year 1957–58, beginning the current era of research and exploration in the region. Scientists today are studying the region’s geology, weather, ecology, life forms, glaciers, water, and climate.

Glacier meltwater is the primary source of the Dry Valley’s rivers and streams, which flow only from December to March during Antarctic summer. The meltwater comes from two large valley glaciers, numerous alpine glaciers, and two piedmont glaciers at the foot of the mountains.

In the Dry Valleys, life occurs wherever there is water. The ecosystem supports many forms of microbial life, including yeast, algae, cyanobacteria, rotifers, nematodes, tardigrades, and springtails, as well as mosses and lichens. Microbes living in such environments—15˚C (59˚F) or colder—are a type of extremophile (an organism that lives in extreme conditions), known as psychrophiles. These organisms display intriguing adaptations that enable them to survive under extreme conditions. Yeasts produce special proteins when freezing or near freezing, which may allow their plasma membrane to freeze and thaw without rupturing. Lithophiles live in tiny pockets of water between grains in rock, obtaining their energy from chemical reactions between the water and the rocks. Still other microorganisms obtain their energy from sulfur and iron; they are responsible for the pigment seen at Blood Falls, a bright red waterfall-like feature at the toe of Taylor Glacier.

Photo Credit: Peter Rejcek, The Antarctice Sun

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