McMurdo Dry Valleys

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Coordinates: 77°28′S 162°31′E / 77.467°S 162.517°E / -77.467; 162.517

"Dry valleys" redirects here. For other uses, see dry valley

Map of the McMurdo Sound and the Dry Valleys.

December 12, 2001 photo of the USGS streamflow-gaging station at Huey Creek, Taylor Valley, Victoria Land.

McMurdo Dry Valleys, Landsat 7 imagery acquired on December 18, 1999.

ASTER image of the dry valleys.

The McMurdo Dry Valleys are a row of valleys in Antarctica located within Victoria Land west of McMurdo Sound.^[1] 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.

Climate

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 0.03 % of the continent, 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.^[2]

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.^[3]

Geology

The valleys cut through the Beacon sandstone. The gravel appears to be derived from two sources. The first is terminal moraines which have formed at the end of glaciers which descend into the Dry Valleys. These glaciers sublime directly to air, for the most part, adding very little liquid water to the valleys. The second potential source of gravel is 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.

Biota

Endolithic photosynthetic bacteria 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.

Unusual bacteria have been found in Blood Falls at the tongue of the Taylor Glacier, above the ice-covered surface of Lake Bonney in Taylor Valley.

Anaerobic bacteria whose metabolism is based on iron and sulphur live in sub-freezing temperatures under the Taylor Glacier, staining the ice emerging at Blood Falls red.^[4][5]

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

Mummified seal carcass in the McMurdo Dry Valleys

Major geographic features

Valleys

• Alatna Valley (sometimes incorrectly spelled Atlanta Valley^[6] is the northernmost, north of Benson Glacier.

From north to south, the three main valleys are

• Victoria Valley (between St. Johns Range in the north and Olympus Range in the south)
• Wright Valley (between Olympus Range in the north and Asgard Range in the south)
• Taylor Valley (between Asgard Range in the north and Kukri Hills in the south)

West of Victoria Valley are, from north to south,

• Barwick Valley
• Balham Valley
• McKelvey Valley

Stretching south from Balham Valley are, from west to east:

• Priscu Valley
• Wall Valley
• Virginia Valley
• Stuiver Valley

West of Taylor Valley is

• Pearse Valley (sometimes incorrectly spelled Pearce Valley).

Further south, between Royal Society Range in the west and the west coast of McMurdo Sound at the lobe of Koettlitz Glacier are, from north to south:

• Garwood Valley
• Marshall Valley
• Miers Valley

Lakes

Some of the lakes of the Dry Valleys rank among the world's most saline lakes, with a higher salinity than Lake Assal (Djibouti) or the Dead Sea. The most saline of all is small Don Juan Pond.

• Lake Vida (Victoria Valley)

• Lake Vanda (Wright Valley)
• Lake Brownworth (Wright Valley) (freshwater)
• Don Juan Pond (Wright Valley)

• Lake Fryxell (Taylor Valley)
• Lake Hoare (Taylor Valley)
• Lake Chad (Taylor Valley)
• Dirty Little Hoare Pond (Taylor Valley)
• Parera Pond (Taylor Valley) (freshwater)
• Lake Bonney (Taylor Valley)

• Lake Joyce (Pearse Valley)

• Lake Garwood (Garwood Valley)
• Lake Miers (Miers Valley)

Rivers

• Kite Stream (Victoria Valley)
• Onyx River (Wright Valley)
• Vincent Creek (Taylor Valley)
• Crescent Stream (Taylor Valley)
• Harnish Creek (Taylor Valley)
• Huey Creek (Taylor Valley)

See also

• John Charles Priscu

References

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, 7–21.
• 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
• Detailed satellite images