Major Deserts of the World
Major Deserts of the World : Antarctica
| Arabian | Atacama
| Chihuahuan | Gobi
| Great Basin | Great
Victoria | Highlands
of Iceland | Kalahari
| Monte | Patagonian
| Sahara | Taklamakan
| Thar
Atacama Desert
The Atacama Desert of Chile is a virtually rainless plateau made up of salt basins (salares), sand, and lava flows, extending from the Andes mountains to the Pacific Ocean. It is 15 million years old and 100 times more arid than California's Death Valley.
The total area of Atacama is 181,300 square kilometers (70,000 mi²). The desert is created from the rain shadow produced by the Andes Mountains to the east of the desert.
Climate
The Atacama Desert is the driest place on Earth, 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 the Chilean region of Antofagasta is just 1 mm per year, and there was a period of time where no rain fell in the entire desert for 400 years. 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, in fact, 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, have possibly been glacier-free throughout the Quaternary - though permafrost extends down to an altitude of 4,400 metres and is continuous above 5,600 metres.
Some locations in the Atacama do receive marine fog, 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 - the crest-line of the coastal range averages 3,000 m for about 100 km south of Antofagasta - 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"
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