McMurdo Dry Valleys

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The McMurdo Dry Valleys are a row of valleys in Antarctica located within Victoria Land west of McMurdo Sound. The region includes many interesting geological features including Lake Vida and the Onyx River, Antarctica's longest river. It is also one of the world's most extreme deserts. From north to south, the three main valleys are Victoria Valley, Wright Valley and Taylor Valley.

The Dry Valleys are so named because of their extremely low humidity and their lack of snow or ice cover. Together, at 4800 square kilometers, they constitute around 2% of the continent,^[1] and form the largest relatively ice-free region in Antarctica. The valley floors are covered with a loose gravelly material, in which ice-wedge polygons may be observed.

The unique conditions in the Dry Valleys are caused by katabatic winds (from the Greek word for 'going down'). These occur when cold, dense air is pulled downhill simply by the force of gravity. The winds can reach speeds of 320 km/h (200 mph) evaporating all moisture - water,ice and snow - in the process. ^[2]

The gravel is often derived from two sources. The first is the terminal moraines which have formed at the end of glaciers which descend into the Dry Valleys but then mostly sublime directly to air. Thus very little liquid water is added. The second source of terminal moraines comes from a rather unusual source. It is believed that during some glacial periods, the quantity of ice in the nearby Ross Sea was so great that it forced its way inland into some of the Dry Valleys, in a kind of reverse glacier and deposited its own terminal moraine.

Endolithic plants have been found living in the Dry Valleys, sheltered from the dry air in the (relatively) moist interior of rocks. Summer meltwater from the Valleys' overhanging glaciers provides the primary source of soil nutrients. Scientists consider the Dry Valleys perhaps the closest of any terrestrial environment to Mars, and thus an important source of insights into possible extraterrestrial life.

Part of the Valleys was designated an environmentally protected area in 2004.

Contents 1 Fiction 2 See also 3 External links 4 References

[edit] Fiction

The McMurdo Dry Valleys and their scientific exploration are a major theme in Kim Stanley Robinson's novel Antarctica.

[edit] See also

• The article on other forms of dry valley.
• McMurdo Sound
• Taylor Glacier
• Lake Vida
• Onyx River
• Lake Fryxell
• Lake Bonney (Antarctica)

[edit] External links

• Map of the McMurdo Dry Valleys area (pdf)
• Another map (USGS)
• Antarctic Connection
• Study: Life in Antarctic ice may compare to Mars
• Special Report: The McMurdo Dry Valleys, Antarctic Sun, January 26 2003
• Virtual Tour of the Dry Valleys
• In Antarctica's Dry Valleys, worms offer clues to alarming changes in ecosystem - The New York Times/International Herald Tribune, November 2006
• A Long-Term Ecological Research group is working in the area.
• Pictures from the Dry Valleys region

[edit] References

1. ^ Lloyd, J & Mitchinson, J: "The Book of General Ignorance". Faber & Faber, 2006.
2. ^ Lloyd, J & Mitchinson, J: "The Book of General Ignorance". Faber & Faber, 2006.

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