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20-523: The McMurdo Dry Valleys are a row of largely snow-free valleys in Antarctica , located within Victoria Land west of McMurdo Sound . The Dry Valleys experience extremely low humidity and surrounding mountains prevent the flow of ice from nearby glaciers . The rocks here are granites and gneisses , and glacial tills dot this bedrock landscape, with loose gravel covering the ground. It

40-553: A century of records, almost exclusively in the form of snow. This contributes to the low humidity of the area. For several weeks in the summer, the temperature increases enough to allow for glacial melt, which causes small freshwater streams to form. These streams feed the lakes at the base of the valleys, which do not have outflow to the sea, causing them to become highly saline. The McMurdo Oasis constitutes approximately 4,000 square kilometres (1,500 sq mi) of "deglaciated mountainous desert", according to McKelvey, bounded by

60-552: A drill designed for sampling on Mars in the permafrost of the driest parts of the valleys, the areas most analogous to the Martian surface. They found no living organisms in the permafrost, the first location on the planet visited by humans with no active microbial life. In 2014, drones were used in the McMurdo Dry Valleys by a team of scientists from Auckland University of Technology (AUT) to create baseline maps of

80-513: A higher salinity than Lake Assal or the Dead Sea . The most saline of all is small Don Juan Pond . Antarctic oasis An Antarctic oasis is a large area naturally free of snow and ice in the otherwise ice-covered continent of Antarctica . In Antarctica there are, in addition to mountaintops and nunataks , other natural snow- and ice-free areas often referred to as "Antarctic oases" or "dry valleys". These areas are surrounded by

100-710: Is interbedded with, the Taylor and Wright Valleys' moraines as basaltic cinder cones and lava flows . These basalts have ages between 2.1 and 4.4 Ma . The Dry Valley Drilling Project (1971–75) determined the Pleistocene layer within the Taylor Valley was between 137 and 275 m thick, and composed of interbedded sandstones , pebble conglomerates , and laminated silty mudstones . This Pleistocene layer disconformably overlies Pliocene and Miocene diamictites . Endolithic bacteria have been found living in

120-474: Is based on iron and sulfur live in sub-freezing temperatures under the Taylor Glacier . It was previously thought that algae were staining the red ice emerging at Blood Falls but it is now known that the staining is caused by high levels of iron oxide . Irish and American researchers conducted a field expedition in 2013 to University Valley in order to examine the microbial population and to test

140-571: Is one of the driest places on Earth, though there are several anecdotal accounts of rainfall within the Dry Valleys. The region is one of the world's most extreme deserts , and includes many features including Lake Vida , a saline lake, and the Onyx River , a meltwater stream and Antarctica's longest river . Although no living organisms have been found in the permafrost here, endolithic photosynthetic bacteria have been found living in

160-421: Is pulled downhill by the force of gravity. The winds can reach speeds of 320 km/h (200 mph), heating as they descend and evaporating all water, ice and snow. The dry wind evaporates the snow rapidly and little melts into the soil. During the summer, this process can take only hours. Another important factor is a lack of precipitation. Precipitation averages around 100 millimetres (4 in) per year over

180-524: Is scoured or sublimated by katabatic winds , leaving the underlying rock exposed. Despite usually extreme aridity , some plants, in the form of bryophytes and lichens , can survive in Antarctic oases. The larger oases (with their respective areas) are: Ross orogeny The Ross orogeny was a mountain building event in Antarctica in the early Paleozoic . The ancestral (also termed proto-) Trans-Antarctic Mountains were uplifted earlier by

200-470: The Antarctic ice sheet or, in coastal areas, are situated between the ice sheet and the Antarctic ice shelves . Antarctic oases and dry valleys develop in areas with particular regional weather patterns and geography. These areas have very low humidity and precipitation . Although these areas are very cold, sufficient solar energy is absorbed by the ground to melt what little snow does fall, or else it

220-571: The Beardmore orogeny but had eroded as a broad epicratonic sea flooded much of Antarctica in the Cambrian . Shallow water sedimentary rocks, platform carbonates and deepwater turbidites from this period are found in the mountain range. The Ross orogeny was one of the most extensive orogenic events in Antarctica, causing widespread plutonism and metamorphism. Bimodal magmatism and extension mark

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240-583: The East Antarctic Ice Sheet from reaching the Ross Sea . At 4,800 square kilometres (1,900 sq mi), the valleys constitute around 0.03% of the continent and form the largest ice-free region in Antarctica. The valley floors are covered with loose gravel, in which ice wedge polygonal patterned ground may be observed. The unique conditions in the Dry Valleys are caused, in part, by katabatic winds ; these occur when cold, dense air

260-746: The Late Cambrian to Early Ordovician , 450-520 Ma , Cambrian sediments within the Transantarctic Mountains were uplifted , folded , metamorphosed , and intruded by granitoid batholiths. Evidence of this origin may be found in the Shackleton Range , the Pensacola Mountains , Thiel Mountains , Horlick Mountains , and the Queen Maud Mountains . This orogeny article is

280-666: The Asgard Formation , which is a medium-high-grade marble and calc schist . The Palaeozoic Granite Harbour intrusives include granitoid plutons and dykes , which intruded into the metasedimentary Skelton Group in the Late Cambrian – Early Ordovician during the Ross orogeny . The basement complex is overlain by the Jurassic Beacon Supergroup , which is itself intruded by Ferrar Dolerite sheets and sills . The McMurdo Volcanic Group intrudes, or

300-402: 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

320-489: The beginnings of the orogeny, while during the later phase sedimentary rocks at the continental margin were deformed, metamorphosed and intruded with granite batholiths . Interpretations of rock forms in Antarctica during the 1980s suggested a westward-dipping subduction zone may have formed along the paleo-Pacific Ocean shoreline of East Antarctica. This is inferred from a large number of I-type and S-type granitoids which are similar to large circum-Pacific batholiths. During

340-604: The coastline of south Victoria Land and the Polar Plateau . The Taylor and Wright Valleys are major ice-free valleys within the Transantarctic Mountains . These "dry valleys" include hummocky moraines , with frozen lakes, saline ponds, sand dunes, and meltwater streams. Basement rocks include the Late Precambrian or Early Palaeozoic Skelton Group metamorphic rocks , primarily

360-573: The relatively moist interior of rocks, and anaerobic bacteria , with a metabolism based on iron and sulfur, live under the Taylor Glacier . The valleys are located within the McMurdo Valleys Antarctic Specially Managed Area (ASMA-2). The Dry Valleys are so named because of their extremely low humidity and lack of snow or ice cover. They are also dry because, in this location, the mountains are sufficiently high that they block seaward-flowing ice from

380-411: The three main valleys are West of Victoria Valley are, from north to south, Stretching south from Balham Valley are, from west to east: West of Taylor Valley is 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: Some of the lakes of the Dry Valleys rank among the world's most saline lakes, with

400-619: The vegetation. In 2015, the New Zealand Antarctic Research Institute granted funding to AUT to develop methods for operating unmanned aerial vehicles . Over successive summer seasons in Antarctica, the AUT team created three dimensional maps with sub-centimeter resolution, which are now used as baselines. Part of the Valleys was designated an environmentally protected area in 2004. From north to south,

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