McMurdo Dry Valleys
The McMurdo Dry Valleys
located in Antarctica is one of the driest places on planet Earth. It is one of the world’s most extreme deserts. Katabatic winds (these occur when cold, dense air is pulled downhill by the force of gravity) reaches speeds of 320 kilometres per hour (200 mph), heating as they descend, and evaporating all water, ice and snow. There is extremely low humidity and lack of snow or ice cover and the mountains are so high that they block seaward flowing ice from the East Antarctic ice sheet from reaching the Ross Sea.
Taylor Dry Valley. Photo from RossSea.info
The McMurdo Dry Valleys region is a cold desert ecosystem – cold, extremely arid and windy. The mean annual temperature here is about –20°C (-4°F) and annual precipitation is less than 100 mm water equivalent. Available water is therefore mainly a result of summer glacial melt. There are only few life forms in these valleys. Only microbial organisms, especially yeasts, can be found at all but the driest sites in the region. Where there is sufficient water algae, cyanobacteria, mosses, lichens and also occur, along with tiny invertebrate animals such as rotifers, tardigrades and nematodes. 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.
Mummified Seal Carcas in McMurdo Dry Valleys. Photo from wikipedia.
The Dry Valleys contain Antarctica’s longest and largest river, the Onyx. The flow of the Onyx has been measured almost constantly since 1970, and the Long Term Ecological Research project also monitors a number of other streams in the Taylor and Wright Valleys. These water flows occur only in summer, with almost all the water provided by glacial melt.
The Onyx river. Photo from RossSea.info
Since 1995, some tourists have visited the Taylor Valley by helicopter, landing near Canada Glacier. Under the Management Plan this site has been designated as a Tourism Zone, and is the only part of Dry Valleys available for tourism.