The
Andes are the world's longest exposed
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 20°S 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. (cordillera occidental, central y oriental). 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 200 km wide throughout its length, except in the Bolivian flexure where it is wide. The islands of the Dutch Caribbean
Aruba,
Bonaire, and
Curaçao, 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
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:
- The Central Volcanic Zone (CVZ) compromising the volcanoes of southern Peru, Bolivia, and northern Chile and Argentina
Ore deposits and evaporites
Climate
Central Andes
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 (14,800–15,800 ft) in the tropical Ecuadorian, Colombian, Venezuelan, and northern Peruvian Andes, rising to 4,800–5,200 m (15,800–17,060 ft) in the drier mountains of southern Peru south to northern Chile south to about 30°S, then descending to on Aconcagua at 32°S, at 40°S, at 50°S, and only in
Tierra del Fuego at 55°S; from 50°S, 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
Chocó and inter-Andean valleys of Colombia. 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 Queñua, 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 and flora. 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.
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.
[ - biodiversityhotspots.org] 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
fishes (c. 1/3 endemic).
The
Vicuña 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 Chocó, 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. 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/or
xeric vegetation, reaching the extreme in the slopes near the virtually lifeless Atacama Desert.
A number of species such as the
Royal Cinclodes and
White-browed Tit-spinetail are associated with
Polylepis, and consequently also
threatened.
Human activity
Map showing cultural influence in the Andes.
The Andes mountains forms 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 (
Huancas,
Chachapoyas,
Cañaris, etc) 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.
Transportation
thumb|left|200px|Troncal 7 ([[Trans-Andes Highway) in the
Venezuelan Andes]]
Several major cities exist in the Andes, among them
Bogotá in Colombia,
Quito in Ecuador,
Mérida, Mérida in Venezuela ,
La Paz in Bolivia, 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.
Photograph of young Peruvian farmers sowing maize and beans.
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.
Potosí in present-day
Bolivia was one of the principal mines of the Spanish Empire in the New World.
Río de la Plata and
Argentina derive their names from the silver of Potosí.
Currently, mining in the Andes of
Chile and
Peru place these countries as the 1
st and 3
rd 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
Potosí 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 bellow).
Argentina
Image:Aconcagua - Argentina - January 2005 - by Sergio Schmiegelow.jpg|Aconcagua, Argentina
Image:Cerro tronador desde lago mascardi 01b.jpg|Tronador, Argentina/Chile
Border between Argentina and Chile
Image:andes - punta arenas.jpg|Torres del Paine, Chile
Image:Llullaillaco.jpg|Llullaillaco, Argentina/Chile
File:Camino de Alta.jpg|Camino de Alta Montaña, Argentina/Chile
Bolivia
Image:Nevado Sajama.jpg|Sajama
Image:Huayna Potosí La Paz - Bolivia.jpg|Huayna PotosíBorder between Bolivia and Chile
Image:Laguna Verde Bolivia.jpg|Licancabur, Bolivia/Chile
Image:Parinacota.jpg|ParinacotaChile
Image:Stgo Abril.jpg|Santiago de Chile on the western slopes of a snowcapped Andes
Image:Cuernos del Paine from Lake Pehoé.jpg|View of Cuernos del Paine in Torres del Paine National ParkColombia
Image:Ritacuba-blanco.jpg|Ritacuba blanco the highest peak of Cordillera Oriental, Colombia.
Image:Nevado del Ruiz by Edgar.png|Nevado del Ruiz, Colombia
Ecuador
Image:Browncanyonquilotoa.jpg|Rift valley near Quilotoa, Ecuador.
Image:Chimborazo from southwest.jpg|Chimborazo, Ecuador
Peru
Image:Alpamayo.jpg|Alpamayo, Peru
Image:El misti.jpg|El Misti, Peru
Venezuela
Image:Bolívar usgs.jpg|Pico Bolívar, Venezuela
File:Pico Humboldt.jpg|Pico Humboldt, Venezuela
