4 December 2009
Dry Valleys, Antarctica

The McMurdo Dry Valleys are a row of valleys west of McMurdo Sound, Antarctica, so named because of their extremely low humidity and lack of snow and ice cover. Photosynthetic bacteria have been found living in the relatively moist interior of rocks. Scientists consider the Dry Valleys to be the closest of any terrestrial environment to Mars.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of about 50 to 300 feet, ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

The broad spectral coverage and high spectral resolution of ASTER provides scientists with critical information for surface mapping and monitoring of dynamic conditions and temporal change.

SOURCE: NASA

The McMurdo Dry Valleys are a row of valleys in Antarctica located within Victoria Land west of McMurdo Sound.[1] The region is one of the world's most extreme deserts, and includes many interesting features including Lake Vida and the Onyx River, Antarctica's longest river.

Credit: Image by Robert Simmon, based on data provided by the NASA GSFC Oceans and Ice Branch and the Landsat 7 Science Team

One of the few areas of Antarctica not covered by thousands of meters of ice, the McMurdo Dry Valleys stand out in this satellite image. For a few weeks each summer temperatures are warm enough to melt glacial ice, creating streams that feed freshwater lakes that lie at the bottom of the valleys. Beneath a cap of ice these lakes remains unfrozen year-round, supporting colonies of bacteria and phytoplankton. Over the past 14 years, however, summers have been colder than usual, and the lakes are becoming more and more frozen. If the trend continues, the biological communities they support may go into hibernation.

Most of Antarctica has cooled along with the Dry Valleys, in contrast to much of the rest of the Earth, which has warmed over the past 100 years. No one knows if the trend is related to global climate, or just a quirk in the weather.

Climate

The unique conditions in the Dry Valleys are caused, in part, by katabatic winds: these occur when cold, dense air is pulled downhill by the force of gravity. The winds can reach speeds of 320 km/h (200 mph), evaporating all water, ice and snow.[3]

Geology

Biota

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.

Endolithicphotosynthetic 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 glaciers provides the primary source of soil nutrients. Scientists consider the Dry Valleys perhaps the closest of any terrestrial environment to the planet Mars, and thus an important source of insights into possible extraterrestrial life. Anaerobic bacteria whose metabolism is based on iron and sulfur live in sub-freezing temperatures under the Taylor Glacier, staining red the ice emerging at Blood Falls.[4][5]

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

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

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.

• Victoria Valley
• Lake Vida
• Wright Valley
• Lake Vanda
• Lake Brownworth (freshwater)
• Don Juan Pond
• Taylor Valley
• Lake Fryxell
• Lake Hoare
• Lake Chad 
• Dirty Little Hoare Pond
• Parera Pond (freshwater)
• Lake Bonney
• Pearse Valley
• Lake Joyce
• Garwood Valley
• Lake Garwood
• Miers Valley
• Lake Miers

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

"Sure, the lion is king of the jungle, but airdrop him into Antarctica, and he's just a penguin's bitch."    — Dennis Miller.

• 1997
• 1977
• Some images available as wallpaper
• Some images available on a royalty-free compilation CD
• Some images available as a poster

The dry valleys are strange: except for a few steep rocks they are the only continental part of Antarctica devoid of ice. Located in the Trans-Antarctic Range, they correspond to a mountain area where evaporation (or rather, sublimation) is more important than snowfall, thus all the ice disappears, leaving dry barren land.

Here a glacier coming from the continental ice field flows down the valley and just dries out. In summer there can be rivers in the Dry Valleys. Moss and some other form of vegetation grow. Some lakes have strange characteristics, like lake Vanda, always covered with ice, but with salt-saturated liquid water underneath and very mysterious biology. Mummified bodies of seals have been found in those parts, hundreds of kilometers from the sea.

The Dry Valleys are a favorite exploration spot for geologists and microbiologists. I've never been there, those pictures were taken by Laura Connor and Effie Jarret who flew over them several times during their remote sensing missions.

If you want more info on the Dry Valleys, there's an excellent site.

SOURCE: The Dry Valleys of Antarctica