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Atacama redirects here; for other uses, see Atacama .
The Atacama Desert is a virtually rainless plateau in South America, covering a strip of land on the Pacificmarker coast of South America, west of the Andes mountains. The Atacama desert is, according to NASAmarker, National Geographicmarker and many other publications, the driest desert in the world. The rain shadow on the leeward side of the Chilean Coast Range, as well as a coastal inversion layer created by the cold offshore Humboldt Current, keep this over 20 million-year-old desert 50 times drier than California'smarker Death Valleymarker. The Atacama occupies in northern Chilemarker, composed mostly of salt basins (salares), sand, and lava flows.

Setting

The Atacama Desert ecoregion, as defined by the Worldwide Fund for Nature (WWF), extends from a few kilometers south of the Chilemarker-Perumarker border to about 30° south latitude. To the north lies the Sechura Desertmarker ecoregion, in Perumarker, whilst to the south is the Chilean Matorral ecoregion. The National Geographic Societymarker considers the coastal area of southern Peru to be part of the Atacama desert, including the deserts south of the Ica Regionmarker.

To the east lies the less arid Central Andean dry puna ecoregion. The drier portion of this ecoregion is located south of the Loa Rivermarker between the parallel Sierra Vicuña Mackennamarker and Cordillera Domeykomarker. To the north of the mentioned river lies the Pampa del Tamarugal.
Image:Atacama desert.jpg|Map of the Atacama Desert (Chilean area) from the CIA World Factbook.Image:Atacama1.jpg|Atacama DesertImage:Valle de la luna san pedro chile.jpg|Scene from Valle de la Luna (Moon Valley) near San Pedro de Atacama.Image:Solar Evaporation Ponds, Atacama Desert.jpg|Solar Evaporation Ponds in the Atacama Desert.


Second driest desert

The Atacama is one of the driest places on Earth, and is virtually sterile because it is blocked from moisture on both sides by the Andes mountains and by the Chilean Coast Range. A coastal inversion layer created by the cold Humboldt Current, and the anticyclone of the Pacific are essential to keep the climate of the Atacama dry. The average rainfall in the Chilean region of Antofagastamarker is just per year. Some weather stations in the Atacama have never received rain. Evidence suggests that the Atacama may not have had any significant rainfall from 1570 to 1971. It is so arid that mountains that reach as high as are completely free of glaciers and, in the southern part from 25°S to 27°S, may have been glacier-free throughout the Quaternary, though permafrost extends down to an altitude of and is continuous above . Studies by a group of British scientists have suggested that some river beds have been dry for 120,000 years.

Some locations in the Atacama do receive a marine fog known locally as the Camanchaca, providing sufficient moisture for hypolithic algae, lichens and even some cacti. But in the region that is in the "fog shadow" of the high coastal crest-line, which averages m height for about south of Antofagasta, the soil has been compared to that of Mars. Due to its otherworldly appearance, the Atacama has been used as a location for filming Mars scenes, most notably in the television series Space Odyssey: Voyage to the Planets.

In 2003, a team of researchers published a report in Science magazine titled "Mars-like Soils in the Atacama Desert, Chile, and the Dry Limit of Microbial Life" in which they duplicated the tests used by the Viking 1 and Viking 2 Mars landers to detect life, and were unable to detect any signs in Atacama Desert soil. The region may be unique on Earth in this regard and is being used by NASAmarker to test instruments for future Mars missions. The Team duplicated the Viking tests in Mars-like Earth environments and found that they missed present signs of life in soil samples from Antarctic dry valleys, the Atacama Desert of Chile and Peru, and other locales.

In 2008, the Phoenix Mars Lander detected perchlorates on the surface of Mars at the same site where water was first discovered. Perchlorates are also found in the Atacama and associated nitrate deposits have contained organics, leading to speculation that signs of life on Mars are not incompatible with perchlorates. Alonso de Ercilla described the desert in La Araucana, published in 1569: "Towards Atacama, near the deserted coast, you see a land without men, where there is not a bird, not a beast, nor a tree, nor any vegetation" (quoted Braudel 1984 p 388). The Atacama is also a testing site for the NASAmarker funded Earth-Mars Cave Detection Program.

Human occupation

Atacama road.
The Atacama is sparsely populated. In an oasis, in the middle of the desert, at about elevation, lies the village of San Pedro de Atacamamarker. Its church was built by the Spanishmarker in 1577. In pre-Hispanic times, before the Inca empire, the extremely arid interior was inhabited mainly by the Atacameño tribe. The tribe is noted for the construction of fortified towns called pucara(s), one of which can be seen a few kilometers from San Pedro de Atacama.

During the 16th, 17th and 18th centuries under the Spanish Empire, towns grew along the coast as shipping ports for silver produced in Potosímarker and other mines.

During the 19th century the desert came under control of Bolivia, Chile and Peru and soon became a zone of conflict due to unclear borders and the discovery of nitrate there. After the War of the Pacific, in which Chile annexed most of the desert, cities along the coast developed into international ports, and many Chilean workers migrated there.

The Escondida Minemarker and Chuquicamatamarker are also located within the Atacama Desert.

The Pan-American Highway runs through the Atacama in a north-south trajectory.

Astronomical observatories

Because of its high altitude, nearly non-existent cloud cover, dry air, and lack of light pollution and radio interference from the very widely spaced cities, the desert is one of the best places in the world to conduct astronomical observations. The European Southern Observatorymarker operates two major observatories in the Atacama:

A new radio astronomy telescope called ALMAmarker, is being built by Europe, Japanmarker, North America, and Chilemarker in the Llano de Chajnantor Observatory. A number of radio astronomy projects are currently operating in the Chajnantor area since 1999. For example: CBI, ASTEmarker, ACTmarker, among others.

Abandoned nitrate mining towns

The desert has rich deposits of copper and other minerals, and the world's largest natural supply of sodium nitrate, which was mined on a large scale until the early 1940s. The Atacama border dispute over these resources between Chile and Bolivia began in the 1800s.

Now the desert is littered with approximately 170 abandoned nitrate (or "saltpeter") mining towns, almost all of which were shut down decades after the invention of synthetic nitrate in Germanymarker at the turn of the 20th century (see Haber Process). The towns include Chacabucomarker, Humberstone, Santa Lauramarker, Pedro de Valdivia, Puelma, Maria Elena and Oficina Anita.

Protected areas



Legends



See also



References

Bibliography

  • Braudel, Fernand, The Perspective of the World, ISBN 0520081161, vol. III of Civilization and Capitalism 1984 (originally published in French, 1979).
  • Sagaris, Lake. Bone and dream : into the world's driest desert. 1st ed. -- Toronto : A.A. Knopf Canada, c2000. ISBN 0676972233


Notes

  1. http://ngm.nationalgeographic.com/ngm/0308/feature3/
  2. http://www.extremescience.com/DriestPlace.htm
  3. http://quest.nasa.gov/challenges/marsanalog/egypt/AtacamaAdAstra.pdf
  4. Tibor, Dunai(Dr.). Amazing Nature. http://www.nature-blog.com/2007/10/atacama-desert-dryest-place-on-earth.html. Retrieved 3/24/08
  5. Viking Mission May Have Missed Mars Life, Study Finds
  6. Giant Penguins Once Roamed Peru Desert, Fossils Show
  7. Thompson, Andrea. Scientists Set Record Straight on Martian Salt Find. http://www.space.com/scienceastronomy/080805-phoenix-perchlorate-update.html. Retrieved 6 August 2008
  8. Earth-Mars Cave Detection Program


External links




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