Atacama Desert

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Coordinates: 24°30′S 69°15′W / 24.5°S 69.25°W / -24.5; -69.25

Atacama redirects here; for the political-administrative region of Chile, see Atacama Region.
Atacama by NASA World Wind
Atacama Desert
Scene from Valle de la Luna (Moon Valley) near San Pedro de Atacama.

The Atacama Desert is a virtually rainless plateau in South America, covering a 966 km (600 mi) strip of land on the Pacific coast of South America, west of the Andes mountains. The Atacama is, according to NASA, National Geographic and many other publications, the driest desert in the world.[1][2][3] The rain shadow on the leeward side of the Chilean Coast Range and the Andes, as well as a coastal inversion layer created by the cold offshore Humboldt Current, keep this over 20 million-year-old desert[4] 50 times drier than California's Death Valley. The Atacama occupies 181,300 square kilometers (70,000 mi²)[5] in northern Chile, composed mostly of salt basins (salares), sand, and lava flows.

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[edit] Setting

The Atacama Desert ecoregion, as defined by the Worldwide Fund for Nature (WWF), extends from a few kilometers south of the Chile-Peru border to about 30° south latitude.[6] To the north lies the Sechura Desert ecoregion, in Peru, whilst to the south is the Chilean Matorral ecoregion. The National Geographic Society considers the coastal area of southern Peru to be part of the Atacama desert,[7][8] including the deserts south of the Ica Region.

To the east lies the less arid Central Andean dry puna ecoregion. The drier portion of this ecoregion is located south of the Loa River and west of the Cordillera Domeyko. To the north of the mentioned river lies the Pampa del Tamarugal.

[edit] Driest desert

The Atacama is one of the driest places on Earth,[9] 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 Antofagasta is just 1 mm 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.[5] It is so arid that mountains that reach as high as 6,885 metres (22,590 feet) 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 4,400 metres and is continuous above 5,600 metres. 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 3,000 m height for about 100 km 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.

Atacama road.

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 NASA 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.[10] 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 NASA funded Earth-Mars Cave Detection Program.[11]

[edit] Human occupation

The Atacama is sparsely populated. In an oasis, in the middle of the desert, at about 2000 meters elevation, lies the village of San Pedro de Atacama. Its church was built by the Spanish 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 Potosí 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 Mine and Chuquicamata are also located within the Atacama Desert.

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

[edit] Astronomical observatories

Because of its high altitude, nearly non-existent cloud cover, 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 Observatory operates two major observatories in the Atacama:

A new radio astronomy observatory, called ALMA, is being built in the Atacama by astronomers from Europe, Japan, and North America. Another radio astronomy observatory, ACT, is being built on Cerro Toco in the Atacama Desert.

[edit] 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 Germany at the turn of the 20th century (see Haber Process).[citation needed] The towns include Chacabuco, Humberstone, Santa Laura, Pedro de Valdivia, Puelma, Maria Elena and Oficina Anita.

One of the best examples of an abandoned mining town is that of Baquedano, which was home to one of the most technologically advanced train stations during the nitrate "white gold" boom of the early 20th century.[citation needed] While it is now almost completely abandoned, the remains of the station are untouched and seldom visited by outsiders. Only a few kilometers from Baquedano, on the Pan-American highway, is one of many makeshift cemeteries housing the remains of indigenous miners who were persuaded to work for the German mining operations. Many of the graves belong to children under the age of five, poisoned by the pollution kicked up during the mining process.[citation needed]

Map of the Atacama Desert (Chilean area) from the CIA World Factbook.

[edit] Protected areas

[edit] Legends

[edit] See also

[edit] References

[edit] Bibliography

[edit] 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. ^ a b Wright, John W. (ed.); Editors and reporters of The New York Times (2006). The New York Times Almanac (2007 ed.). New York, New York: Penguin Books. pp. 456. ISBN 0-14-303820-6. 
  6. ^ "Terrestrial Ecoregions -- Atacama desert (NT1303)". www.worldwildlife.org. http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt1303_full.html. Retrieved on 2008-03-11. 
  7. ^ Viking Mission May Have Missed Mars Life, Study Finds
  8. ^ Giant Penguins Once Roamed Peru Desert, Fossils Show
  9. ^ Boehm, Richard G.; Editors and writers of The World and Its People (2006). The World and Its People (2005 ed.). Columbus, Ohio: Glencoe. pp. 276. ISBN 0-07-860977-1. 
  10. ^ Thompson, Andrea. Scientists Set Record Straight on Martian Salt Find. http://www.space.com/scienceastronomy/080805-phoenix-perchlorate-update.html. Retrieved 6 August 2008
  11. ^ [Earth-Mars Cave Detection Program]

[edit] External links


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See also: List of deserts and List of deserts by area
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