Andes

Andes range (Quechua: Anti(s/kuna))
Range
Aerial photo of a portion of the Andes between Argentina and Chile
Countries  Argentina,  Bolivia,  Chile,  Colombia,  Ecuador,  Peru,  Venezuela
Cities Bogotá, Santiago, Medellín, La Paz, Cali, Quito, Cúcuta, Bucaramanga, Arequipa, Cusco, Mendoza, Cuenca, Cochabamba, Pereira, Ibagué, Salta
Highest point Aconcagua
 - location Argentina
 - elevation 6,962 m (22,841 ft)
 - coordinates
Length 7,000 km (4,350 mi)
Width 500 km (311 mi)
Composite satellite image of the southern Andes

The Andes are the world's longest continental mountain range. It is a continuous chain of highland along the western coast of South America. The range is over 7,000 km (4,300 mi) long, 200 km (120 mi) to 700 km (430 mi) wide (widest between 18° to 20°S latitude), and of an average height of about 4,000 m (13,000 ft).

Over its length, the Andean range is split into several ranges, separated by intermediate depressions. The Andes hosts several high plateaux some of which has mayor cities such as Quito, Bogotá, Cuzco and La Paz. The Altiplano plateaux is the second highest plateau after the Tibet. 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 6,962 m (22,841 ft) 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.

Contents

Name

There are many theories about the etymology of the name Andes. Some believe Andes derives from the Quechua word anti, which means "high crest". Some believe Andes derives from one of the four regions of the Inca empire, or Anti(s). Some believe Andes derives from the Spanish word andén which means terrace in reference to the cultivation terraces used by the Incas and other related peoples. Some believe Andes is Spanish shorthand for "Andenes" or "Andenerías".

Geography

Aerial view of Aconcagua.

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). In the northern part the isolated Sierra Nevada de Santa Marta range is often considered part of the Andes. The eastern range is the only one that extends to Venezuela.[1] The term cordillera comes from the Spanish word meaning 'rope'. The Andes range is approximately 200 km (124 mi) wide throughout its length, except in the Bolivian flexure where it is 640 km (398 mi) 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

Geology of the Andes
The Andes
Orogenies
Pampean orogeny
Famatinian orogeny
Gondwanide orogeny
Andean orogeny
Fold-thrust belts

Central Andean | Patagonian
Batholiths
Peruvian Coastal | North Patagonian | South Patagonian
Subducted structures

Antarctic Plate | Carnegie Ridge | Chile Rise | Farallon Plate (formerly) | Juan Fernández Ridge | Nazca Plate | Nazca Ridge
Faults

Gastre | Liquiñe-Ofqui | Magallanes-Fagnano
Andean Volcanic Belt

Northern Zone| Peruvian flat-slab | Central Zone | Pampean flat-slab | Southern Zone | Patagonian Gap | Austral Zone
Paleogeographic terminology

Arequipa-Antofalla Terrane | Chilenia | Chiloé Block | Cuyania | Iapetus Ocean | Madre de Dios Terrane | Mejillonia | Pampia

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. The rise of the Andes has not been been even and different regions have had different degress of tectonic stress, uplift, and erosion.

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 1,000 km (620 mi) 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

Rift valley near Quilotoa, Ecuador.
Astronaut photograph with the high plains of the Andes Mountains in the foreground, with a line of young volcanoes facing the much lower Atacama Desert.

The Andes range has many active volcanoes, which are distributed in four volcanic zones separated by areas of inactivity. The Andean volcanism is a result of subduction of the Nazca Plate and Antarctic Plate underneath the South American Plate. The belt is subdivided into four main volcanic zones that are separed from each other by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products and morphology. While some differences can be explained by which volcanic zone a volcano belongs to, there significant differences inside volcanic zones and even between neighboring volcanoes. Despite being a type location for calc-alkalic and subduction volcanism, the Andean Volcanic Belt has a large range of volcano-tectonic settings, such as rift systems and extrensional zones, transpressional faults, subduction of mid-ocean ridges and seamount chains apart from a large range on crustal thicknesses and magma ascent paths, and different amount of crustal assimilations.

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 18 °C (64 °F) 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 4,500 m (14,760 ft) on Aconcagua at 32°S, 2,000 m (6,600 ft) at 40°S, 500 m (1,640 ft) at 50°S, and only 300 m (980 ft) in Tierra del Fuego at 55°S; from 50°S, several of the larger glaciers descend to sea level.[2]

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. 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.[3] 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 4,500 m (14,760 ft) 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.[4]

Fauna

A male Andean Cock-of-the-rock, a species found in humid Andean forests.
Herds of llamas (alpacas) on the mountain Ausangate hillside.

The Andes are 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.[3] 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).[3]

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 4,000 m (13,100 ft), 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.

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 form a north-south axis of cultural influences. A long series of cultural development culminated in the expansion of the Inca civilization and Inca Empire in the central Andes during the 15th century. The Incas formed this civilization through imperialistic militarism as well as careful and meticulous governmental management.[5] The government sponsored the construction of aqueducts and roads in addition to preexisting installations. Some of these constructions are still in existence today.

Main article: Spanish conquest of Peru

Devastated by European diseases to which they had no immunity, and civil wars, in 1532 the Incas were defeated by an alliance composed of tens of thousands allies from nations they had subjugated (e.g. Huancas, Chachapoyas, Cañaris) and a small army of 180 Spaniards led by Francisco Pizarro. One of the few Inca sites the Spanish never found in their conquest was Machu Picchu, which lay hidden on a peak on the eastern 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.

In modern times, the largest interandean cities are Bogotá 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 reaches from a few metres above sea level to approximately 950 metres (Chosica district).

Transportation

Troncal 7 (Trans-Andes Highway) in the Venezuelan Andes.

Several major cities exist in the Andes, among them Bogotá and Cali in Colombia, Quito in Ecuador, Mérida 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.[1] 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

Photograph of young Peruvian farmers sowing maize and beans.

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. 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 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 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 below).

Argentina

Aconcagua, Argentina

Tronador, Argentina/Chile

Border between Argentina and Chile

Torres del Paine, Chile
Llullaillaco, Argentina/Chile
Camino de Alta Montaña, Argentina/Chile

Bolivia

Sajama

Huayna Potosí

Border between Bolivia and Chile

Licancabur, Bolivia/Chile

Parinacota

Chile

Santiago de Chile on the western slopes of a snowcapped Andes

View of Cuernos del Paine in Torres del Paine National Park

Colombia

Ritacuba blanco the highest peak of Cordillera Oriental, Colombia.

Nevado del Ruiz, Colombia

Ecuador

Rift valley near Quilotoa, Ecuador.

Chimborazo, Ecuador

Peru

Alpamayo, Peru

El Misti, Peru

Venezuela

Pico Bolívar, Venezuela

Pico Humboldt, Venezuela

Notes

  1. ↑ 1.0 1.1 Andes travel map
  2. ↑ "Climate of the Andes". http://www.blueplanetbiomes.org/andes_climate_page.htm. Retrieved 2007-12-09. 
  3. ↑ 3.0 3.1 3.2 Tropical Andes - biodiversityhotspots.org
  4. ↑ "Plants of the Andes". http://www.blueplanetbiomes.org/andes_plant_page.htm. Retrieved 2007-12-09. 
  5. ↑ D'Altroy, Terence N. The Incas. Blackwell Publishing, 2003

See also

References

External links

Subfields of physical geography

Biogeography · Climatology / Paleoclimatology · Coastal geography · Geomorphology · Glaciology · Hydrology / Hydrography · Landscape ecology · Limnology · Oceanography · Palaeogeography · Pedology · Quaternary science

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