Andes

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This article is about the mountain system in South America; for other uses, see Andes (disambiguation).

Image:Andes Chile Argentina.jpg Image:Nasa anden.jpg The Andes are a vast mountain system forming a continuous chain of highland along the western coast of South America. It is roughly 7000 km (4400 mi) long, 500 km (300 mi) wide in some parts (widest between 18° to 20° S latitude), and of an average height of about 4000 m (13,000 ft).

The Andean range is composed of two great principal chains with a deep intermediate depression, in which arise other chains of minor importance, the chief of which is Chile's Cordillera de la Costa. Other small chains arise on the sides of the great chains. The Cordillera de la Costa starts from the southern extremity of the continent and runs in a northerly direction, parallel with the coast, being broken up at its beginning into a number of islands and afterwards forming the western boundary of the great central valley of Chile. To the north this coastal chain continues in small ridges or isolated hills along the Pacific Ocean as far as Venezuela, always leaving the same valley more or less visible to the west of the western great chain. The mountains extend over seven countries: Argentina, Bolivia, Chile, Colombia, Ecuador, Peru and Venezuela.

The Andes are the highest mountain range outside Asia, with the highest peak, Aconcagua, rising to 6,959 m above sea level. The summit of Mount Chimborazo in the Ecuadorean Andes is the point on the Earth's surface most distant from its centre, due to the equatorial bulge. The Andes cannot match the Himalaya in height but do so in width and are more than twice as long.

1 Physical features
2 The people
- 2.1 Peaks
3 External links

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Physical features

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Geology

The formation of the Andes extends into the Paleozoic Era, when terrane accretion was the dominant process. It was during the Cretaceous Period that the Andes began to take their present form, by the uplifting, faulting and folding of sedimentary and metamorphic rocks of the ancient cratons to the east. Tectonic forces along the subduction zone along the entire west coast of South America where the Nazca Plate and a part of the Antarctic Plate are sliding beneath the South American Plate continue to produce an ongoing orogenic event resulting in minor to major earthquakes and volcanic eruptions to this day. In the extreme south a major transform fault separates Tierra del Fuego from the small Scotia Plate. Across the 1000 km wide Drake Passage lie the mountains of the Antarctic Peninsula south of the Scotia Plate which appear to be a continuation of the Andes chain.

The Andes mountains have many active volcanoes, the most famous being the Cotopaxi, one of the highest active volcanos in the world.

The Andes can be divided into three broad categories: the Southern Andes in Argentina and Chile; the Central Andes, including the Chilean and Peruvian cordilleras; and the northern section in Venezuela, Colombia, and northern Ecuador consisting of two parallel ranges, the Cordillera Occidental and the Cordillera Oriental. The term cordillera comes from the Spanish word meaning 'rope'. The Andes range is approximately 200-300 km wide throughout its length, except in the Bolivian flexure where it is 640 km wide [1] [2].

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Climate

The climate in the Andes varies greatly depending on location, altitude, proximity to the sea. The southern section is rainy and cool, the central Andes are dry. The northern Andes are typically rainy and warm, with an average temperature of 18 °C in Colombia. The climate is known to change drastically. Tropical rainforests exist just miles away from the snow covered peak, Cotopaxi. The mountains have a large effect on the temperatures of nearby areas. The snow line depends on the location. It is at between 4500-4800 m in the tropical Ecuadorian, Colombian, Venezuelan, and northern Peruvian Andes, rising to 4800-5200 m in the drier mountains of southern Peru south to northern Chile south to about 30°S, then descending to 4500m on Aconcagua at 32°S, 2000 m at 40°S, 500 m at 50°S, and only 300 m in Tierra del Fuego at 55°S; from 50°S, several of the larger glaciers descend to sea level (Google Earth images). Image:Andes - punta arenas.jpg

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Plant and animal life

Tropical rainforests encircle the northern Andes. The cinchona, a source of quinine which is used to treat malaria, is found in the Bolivian Andes. The high-altitude Polylepis forests are present in the Andean areas of Ecuador, Peru and Bolivia. The trees, Queñua, Yagual, Quinua and other names that local people use to call them, can be found at altitudes of 4500 m above sea level. Once abundant, the forests began disappearing during the Incan period when much of it was used for building material and cooking fuel. The trees are now considered to be highly endangered with only 10 percent of the original forests remaining [3].

The llama can be found living at high altitudes, predominantly in the Peru and Bolivia. The alpaca, a type of llama, is raised for its wool. The nocturnal chinchilla, an endangered member of the rodent order, inhabits the Andes' alpine regions. The South American condor is the largest bird of its kind in the Western hemisphere. Other animals include the guemul, puma, camelids and, for birds, the partridge, parina, huallata, and coot. Llamas and pumas play important roles in many Andean cultures.