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Andes


The Andes are the world's longest continental mountain range. They lie as a continuous chain of highland along the western coast of South America. The range is over long, to wide (widest between 18 to 20S latitude), and of an average height of about .

Over its length the Andean range is at several locations split into several ranges, often two great ranges, named Cordillera Oriental and the Cordillera Occidental, often separated by a intermediate depression. The Andes mountains extend over seven countries: Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, and Venezuela, some of which are known as Andean States.

The Andes mountain range is the highest mountain range outside Asia. The highest peak, Aconcagua, rises to above sea level. The summit of Mount Chimborazo in the Ecuadorean Andes is the point on the Earth's surface most distant from its center, because of the equatorial bulge.

Geography

The Andes can be divided into three sections: the Southern Andes in Argentina and Chile; the Central Andes, including the Chilean and Peruvian cordilleras and parts of Bolivia; and the northern section in Venezuela, Colombia, and Ecuador consisting of two parallel ranges, the Cordillera Occidental and the Cordillera Oriental. In Colombia, north to the border with Ecuador, the Andes split in three parallel ranges, western, central and eastern. . The eastern range is the only one that extends to Venezuela. The term cordillera comes from the Spanish word meaning 'rope'. The Andes range is approximately wide throughout its length, except in the Bolivian flexure where it is wide. The islands of the Dutch Caribbean Aruba, Bonaire, and Curacao, which lie in the Caribbean Sea off the coast of Venezuela, represent the submerged peaks of the extreme northern edge of the Andes range.

Geology

The Andes is a Mesozoic-Tertiary orogenic belt of mountains along the Pacific Ring of Fire, a zone of volcanic activity and orogeny that encompasses the Pacific rim of the Americas as well as the Asia-Pacific region. The Andes are the result of plate tectonics processes, caused by the subduction of oceanic crust beneath the South American plate. The main cause of the rise of the Andes is the compression of western rim of the South American Plate due to the subduction of the Nazca Plate and the Antarctic Plate. To the east the Andes is bounded by several sedimentary basins such as Orinoco, Amazon Basin, Madre de Dios and Gran Chaco which separates the Andes from the ancient cratons in eastern South America. In the south the Andes shares a long boundary with the former Patagonia Terrane. To the west the Andes ends at the Pacific Ocean, although the Peru-Chile trench can be considerated its ultimate western limit. From a geographical approach the Andes is considered to have its western boundaries marked by the apparition of coastal low lands and a less abrupt topography.

Orogeny

The western rim of the South American Plate has been the place of several pre-Andean orogenies since at least the Pampean orogeny of late Proterozoic. These early orogenic events led to amalgamation of several terranes and microcontinents onto the South American part of Gondwana.

The formation of the modern Andes began in the Jurassic Period. 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 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.

Volcanism

The Andes range has many active volcanoes, which are distributed in four volcanic zones separated by areas of inactivity:

*Bucaramanga flat-slab segment

The Northern Volcanic Zone (NVZ) that includes the volcanoes of southern Colombia and Ecuador.

*Peruvian flat-slab segment

The Central Volcanic Zone (CVZ) compromising the volcanoes of southern Peru, Bolivia, and northern Chile and Argentina

*Pampean flat-slab segment

The Southern Volcanic Zone (SVZ), spanning from Central Chile to the Chile Triple Junction

*Patagonian Volcanic Gap

The Austral Volcanic Zone (AVZ) begins south of the Chile Triple Junction and is caused by the subduction of the Antarctic Plate

Ore deposits and evaporites

Climate

The climate in the Andes varies greatly depending on location, altitude, and 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 in Colombia. The climate is known to change drastically in rather short distances. 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 4,500–4,800 m in the tropical Ecuadorian, Colombian, Venezuelan, and northern Peruvian Andes, rising to 4,800–5,200 m in the drier mountains of southern Peru south to northern Chile south to about 30S, then descending to on Aconcagua at 32S, at 40S, at 50S, and only in Tierra del Fuego at 55S; from 50S, several of the larger glaciers descend to sea level.

The Andes of Chile and Argentina can be divided in two climatic and glaciological zones; the Dry Andes and the Wet Andes. Since the Dry Andes extends from the latitudes of Atacama Desert to the area of Maule River, precipitation is more sporadical and there are strong temperature oscillations. The line of equilibrium may shift drastically over short periods of time, leaving a whole glacier in the ablation area or in the accumulation area.

Flora

Rainforests used to encircle much of the northern Andes but are now greatly diminished, especially in the Choco and inter-Andean valleys of Colombia. As a direct opposite of the humid Andean slopes are the relatively dry Andean slopes in most of western Peru, Chile and Argentina. Along with several Interandean Valles, they are typically dominated by deciduous woodland, shrub and xeric vegetation, reaching the extreme in the slopes near the virtually lifeless Atacama Desert.

About 30,000 species of vascular plants live in the Andes with roughly half being endemic to the region, surpassing the diversity of any other hotspot. The small tree Cinchona pubescens, a source of quinine which is used to treat malaria, is found widely in the Andes as far south as Bolivia. Other important crops that originated from the Andes are tobacco and potatoes. The high-altitude Polylepis forests and woodlands are found in the Andean areas of Colombia, Ecuador, Peru, Bolivia and Chile. These trees, by locals referred to as Quenua, Yagual and other names, can be found at altitudes of above sea level. It remains unclear if the patchy distribution of these forests and woodlands is natural, or the result of clearing which began during the Incan period. Regardless, in modern times the clearance has accelerated, and the trees are now considered to be highly endangered, with some believing that as little as 10% of the original woodland remains.

Fauna

The Andes is rich in fauna: With almost 1,000 species, of which roughly 2/3 are endemic to the region, the Andes is the most important region in the world for amphibians.

Animal diversity in the Andes is high, with almost 600 species of mammals (13% endemic), more than 1,700 species of birds (c. 1/3 endemic), more than 600 species of reptiles (c. 45% endemic), and almost 400 species of fish (c. 1/3 endemic).

The Vicuna and Guanaco can be found living in the Altiplano, while the closely related domesticated Llama and Alpaca are widely kept by locals as pack animals and for their meat and wool. The nocturnal chinchillas, two threatened members of the rodent order, inhabits the Andes' alpine regions. The Andean Condor, the largest bird of its kind in the Western Hemisphere, occurs throughout much of the Andes but generally in very low densities. Other animals found in the relatively open habitats of the high Andes include the huemul, cougar, foxes in the genus Pseudalopex, and, for birds, certain species of tinamous (notably members of the genus Nothoprocta), Andean Goose, Giant Coot, flamingos (mainly associated with hypersaline lakes), Lesser Rhea, Andean Flicker, Diademed Sandpiper-Plover, miners, sierra-finches and diuca-finches.

Lake Titicaca hosts several endemics, among them the highly endangered Titicaca Flightless Grebe and Titicaca Water Frog. A few species of hummingbirds, notably some hillstars, can be seen at altitudes above , but far higher diversities can be found at lower altitudes, especially in the humid Andean forests ("cloud forests") growing on slopes in Colombia, Ecuador, Peru, Bolivia and far northwestern Argentina. These forest-types, which includes the Yungas and parts of the Choco, are very rich in flora and fauna, although few large mammals exists, exceptions being the threatened Mountain Tapir, Spectacled Bear and Yellow-tailed Woolly Monkey.

Birds of humid Andean forests include mountain-toucans, quetzals and the Andean Cock-of-the-rock, while mixed species flocks dominated by tanagers and Furnariids commonly are seen - in contrast to several vocal but typically cryptic species of wrens, tapaculos and antpittas.

A number of species such as the Royal Cinclodes and White-browed Tit-spinetail are associated with Polylepis, and consequently also threatened.

Human activity

The Andes mountains form a north-south axis of cultural influences. The Inca Empire developed in the central Andes during the 15th century. The Incas formed this civilization through imperialistic militarism as well as careful and meticulous governmental management. The government sponsored the construction of aqueducts and roads, some of which, like those created by the Romans a thousand years before them, are still in existence today.

Devastated by European diseases to which they had no immunity, and civil war, in 1532 the Incas were defeated by an alliance composed of tens of thousands allies from nations they had subjugated and a small army of 180 Spaniards led by Pizarro. One of the few Inca cities the Spanish never found in their conquest was Machu Picchu, which lay hidden on a peak on the edge of the Andes where they descend to the Amazon. The main surviving languages of the Andean peoples are those of the Quechua and Aymara language families. Woodbine Parish and Joseph Barclay Pentland surveyed a large part of the Bolivian Andes from 1826 to 1827.

Nowadays, the largest Andean cities are Bogota in Colombia with a population of 8 million and Santiago in Chile. The largest city of the Andean zone is the Peruvian capital, Lima, which is located a few meters above sea level.

Transportation

Several major cities exist in the Andes, among them Bogota and Cali in Colombia, Quito in Ecuador, Merida in Venezuela , La Paz in Bolivia, and Arequipa and Cusco in Peru. These and most other cities are now connected with asphalted roads, while smaller towns are often connected by dirt roads, which may require a 4x4 vehicle. Because of the arduous terrain, localities where vehicles are of little use remain. Locally, Llamas continue to play an important role as pack animals, but this use has generally diminished in modern times.

Agriculture

The ancient peoples of the Andes such as the Incas have practiced irrigation techniques for over 6,000 years. Because of the mountain slopes, terracing has been a common practice. Terracing, however, was only extensively employed after Incan imperial expansions to fuel their expanding realm. The potato holds a very important role as an internally consumed staple crop. Maize was also an important crop for these people. However, they were mainly used for the production of the culturally important chicha. Currently, tobacco, cotton and coffee are the main export crops. Coca, despite eradication programmes in some countries, remains an important crop for legal local use in a mildly stimulating herbal tea, and, both controversially and illegally, for the production of cocaine.

Mining

The Andes rose to fame for its mineral wealth during the Spanish conquest of South America. Although Andean Amerindian peoples crafted ceremonial jewelry of gold and other metals the mineralizations of the Andes were first mined in large scale after the Spanish arrival. Potosi in present-day Bolivia was one of the principal mines of the Spanish Empire in the New World. Rio de la Plata and Argentina derive their names from the silver of Potosi.

Currently, mining in the Andes of Chile and Peru place these countries as the 1st and 3rd major producers of copper in the world. The Bolivian Andes produce principally tin although historically silver mining had a huge impact on the economy of 17th century Europe.

There is a long history of mining in the Andes, from the Spanish silver mines in Potosi in the 16th century to the vast current porphyry copper deposits of Chuquicamata and Escondida in Chile and Toquepala in Peru. Other metals including iron, gold and tin in addition to non-metallic resources are also important.

Peaks

This list contains some of the major peaks in the Andes mountain range. The highest peak is Aconcagua of Argentina (see below).

Argentina

Aconcagua,

Cerro Bonete,

Galan,

Mercedario,

Pissis,

Border between Argentina and Chile

Cerro Bayo,

Cerro Chalten, or 3,405 m, Patagonia, also known as Cerro Fitz Roy

Cerro Escorial,

Cordon del Azufre,

Falso Azufre,

Incahuasi,

Lastarria,

Llullaillaco,

Maipo,

Marmolejo,

Ojos del Salado,

Olca,

Sierra Nevada de Lagunas Bravas,

Socompa,

Nevado Tres Cruces, 6,749 m (south summit) (III Region)

Tronador,

Tupungato,

Nacimiento,

File:Camino de Alta.jpg|

Camino de Alta Montana, Argentina/Chile

Bolivia

Ancohuma,

Cabaray,

Chacaltaya,

Huayna Potosi,

Illampu,

Illimani,

Macizo de Larancagua,

Macizo de Pacuni,

Nevado Anallajsi,

Nevado Sajama,

Patilla Pata,

Tata Sabaya,

Border between Bolivia and Chile

Acotango,

Cerro Minchincha,

Irruputuncu,

Licancabur,

Olca,

Parinacota,

Paruma,

Pomerape,

Chile

Monte San Valentin,

Cerro Paine Grande, c.

Cerro Maca, c.

Monte Darwin, c.

Volcan Hudson, c.

Cerro Castillo Dynevor, c.

Mount Tarn, c.

Polleras,

Colombia

Nevado del Huila,

Nevado del Ruiz,

Nevado del Tolima,

Pico Pan de Azucar,

Ritacuba Negra,

Nevado del Cumbal,

Cerro Negro de Mayasquer,

Ritacuba Blanco,

Nevado del Quindio,

Purace,

Santa Isabel,

Dona Juana,

Galeras,

Azufral.

Ecuador

Antisana,

Cayambe,

Chimborazo,

Corazon,

Cotopaxi,

El Altar,

Illiniza,

Pichincha,

Quilotoa,

Reventador,

Sangay,

Tungurahua,

Titicacha,

Peru

Alpamayo,

Artesonraju,

Carnicero,

El Misti,

El Toro,

Huascaran,

Jirishanca,

Nevado de Huaytapallana,

Pumasillo,

Rasac,

Rondoy,

Sarapo,

Seria Norte,

Siula Grande,

Yerupaja,

Yerupaja Chico,

Venezuela

Pico Bolivar,

Pico Humboldt,

Pico Bonpland, }

Pico La Concha,

Pico Piedras Blancas,

File:Pico Humboldt.jpg|Pico Humboldt, Venezuela

See also

Andean Geology - a scientific journal

Apu (god)

Cordillera Mountains in the Philippines

References

John Biggar, The Andes: A Guide For Climbers, 3rd. edition, 2005, ISBN 0-9536087-2-7

Tui de Roy, The Andes: As the Condor Flies. 2005, ISBN 1-55407-070-8

Fjeldsa, J., & N. Krabbe (1990). The Birds of the High Andes. Zoological Museum, University of Copenhagen, Copenhagen. ISBN 87-88757-16-1

Fjeldsa, J. & M. Kessler. 1996. Conserving the biological diversity of Polylepis woodlands of the highlands on Peru and Bolivia, a contribution to sustainable natural resource management in the Andes. NORDECO, Copenhagen.

External links

Andes geology (University of Arizona)

Climate and animal life of the Andes

http://www.peaklist.org/WWlists/ultras/southamerica.html Complete list of mountains in South America with a prominence of at least

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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Andes


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