Atacama
For the politico-administrative region of Chile, see Atacama Region.
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Atacama |
The
Atacama desert of
Chile and
Peru is a virtually rainless
plateau made up of
salt basins (
salares), sand, and
lava flows, extending from the
Andes mountains to the
Pacific Ocean.
The average width (east-and-west) is less than 160 kilometers (100 miles) but it extends from the
Peruvian border 1000 kilometers (600 miles) south to the
Bolivian
Altiplano. The mountains nearest to the ocean are the Pacific coastal range, with an average elevation of 800 meters (2500 feet). The
Cordillera Domeyko, a range of foothills of the
Andes Mountains, lies east.
The Atacama Desert is the driest desert on
Earth (except perhaps for the
McMurdo Dry Valleys in
Antarctica) and is virtually sterile because it is blocked from moisture on both sides by the Andes mountains and by coastal mountains. The average rainfall in
Antofagasta — a region in Chile which is part of the Atacama — is just 3 mm per year, and there was a period of time where no rain fell there for 40 years. The Atacama is 15 million years old and 50 times more arid than California's
Death Valley. It is so arid, in fact, that mountains that reach as high as 6885 metres (22590 feet) are completely free of
glaciers and, in the southern part from 25°S to 27°S, have possibly been glacier-free throughout the
Quaternary, though
permafrost extends down to an altitude of 4400 metres and is continuous above 5600 metres. The Atacama north of 25°S is arid and receives very little rain. However many locations in the desert receive marine fog, providing sufficient moisture for hypolithic algae, lichens and even cacti. In the region south of Antofagasta the coastal range blocks the marine fog. The crest-line of the coastal range averages 3000 m for about 100 km south of Antofagasta. The driest part of the Atacama is between the coastal mountains and the
Cordillera Domeyko, an area called the 'double
rain shadow.' In this region, the Andes block moisture from the east, the
Cordillera Domeyko block runoff from the Andes and the Coastal mountains block marine fog from the ocean. The region that is in the "fog shadow" of this high coastal crest-line is the region that contains the driest soils - the soil has been compared to that of Mars.
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. Alonso de Ercilla characterized it 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 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 between Chile and Bolivia began in the 1800s over these resources.
The Atacama is inhabited, though sparsely populated. The
Pan-American Highway runs through the Atacama. In an
oasis, in the middle of the desert, at an
altitude of some 2000 meters, is the village of
San Pedro de Atacama. Its
church was built by the
Spanish in
1577, but archeological evidence indicates that the San Pedro area was the center of a
Paleolithic civilization that built rock fortresses on the steep mountains encircling the valley. The
Escondida Mine and
Chuquicamata are also located within the Atacama.
The
European Southern Observatory operates two major
observatories in the Atacama desert:
* The
La Silla Observatory* The
Paranal Observatory, which includes the
Very Large Telescope.
*
News article on "Mars-like Soils in the Atacama Desert, Chile, and the Dry Limit of Microbial Life"*
National Geographic feature about Atacama*
Autonomous Robot Finds Life in Atacama Desert*
Atacama's Super-Dry History*
Web Site of the San Pedro de Atacama*
Photo Gallery of the Atacama Desert*
Braudel, Fernand,
The Perspective of the World, vol. III of
Civilization and Capitalism 1984 (in French 1979).
