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Andes
Andes
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The Andes (/ˈændz/ AN-deez Ananta), Andes Mountains or Andean Mountain Range (Spanish: Cordillera de los Andes; Quechua: Anti) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is 8,900 km (5,500 mi) long and 200 to 700 km (120 to 430 mi) wide (widest between 18°S and 20°S latitude) and has an average height of about 4,000 m (13,000 ft). The Andes extend from south to north through seven South American countries: Argentina, Chile, Bolivia, Peru, Ecuador, Colombia, and Venezuela.

Key Information

Along their length, the Andes are split into several ranges, separated by intermediate depressions. The Andes are the location of several high plateaus—some of which host major cities such as Arequipa, Bogotá, Cali, Medellín, El Alto, La Paz, Mérida, Santiago and Sucre. The Altiplano Plateau is the world's second highest after the Tibetan Plateau. These ranges are in turn grouped into three major divisions based on climate: the Tropical Andes, the Dry Andes, and the Wet Andes.

The Andes are the highest mountain range outside of Asia. The range's highest peak, Argentina's Aconcagua, rises to an elevation of about 6,961 m (22,838 ft) above sea level. The peak of Chimborazo in the Ecuadorian Andes is farther from the Earth's center than any other location on the Earth's surface, due to the equatorial bulge resulting from the Earth's rotation. The world's highest volcanoes are in the Andes, including Ojos del Salado on the Chile–Argentina border, which rises to 6,893 m (22,615 ft).

The Andes are also part of the American Cordillera, a chain of mountain ranges (cordillera) that consists of an almost continuous sequence of mountain ranges that form the western "backbone" of the Americas and Antarctica.

Etymology

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The etymology of the word Andes has been debated. The majority consensus is that it derives from the Quechua word anti "east"[1] as in Antisuyu (Quechua for "east region"),[1] one of the four regions of the Inca Empire. Others suggest that it is in fact from the word anta (meaning copper) of the older Aymara language.[2]

The term cordillera comes from the Spanish word cordel "rope"[3] and is used as a descriptive name for several contiguous sections of the Andes, as well as the entire Andean range, and the combined mountain chain along the western part of the North and South American continents.

Geography

[edit]
Aconcagua, in Argentina, the highest mountain in the Western Hemisphere

The Andes mountain range, the longest continental mountain system in the world[4], extends approximately 7,000 km (4,300 mi) along the western edge of South America, spanning seven countries. Its width varies from 200 km (120 mi) to 700 km (430 mi), encompassing a series of parallel cordilleras, high plateaus, and deep intermontane valleys. Prominent peaks such as Aconcagua at 6,961 metres (22,838 feet) in Argentina, Huascarán at 6,768 metres (22,205 feet) in Peru, and Illimani 6,438 metres (21,122 feet) in Bolivia illustrate the extreme elevations and rugged relief that define the range.[5]

The Andes encompass a wide variety of climatic and ecological zones, ranging from humid cloud forests on the eastern slopes to the arid high plains of the Altiplano and the glaciated summits of the southern Andes. These sharp environmental gradients have strongly influenced human settlement and the development of major highland cities such as Bogotá, Cusco, La Paz and Quito.

The Andes can be divided into three sections:

At the northern end of the Andes, the separate Sierra Nevada de Santa Marta range is often, but not always, treated as part of the Northern Andes.[6]

The Leeward Antilles islands Aruba, Bonaire, and Curaçao, which lie in the Caribbean Sea off the coast of Venezuela, were formerly thought to represent the submerged peaks of the extreme northern edge of the Andes range, but ongoing geological studies indicate that such a simplification does not do justice to the complex tectonic boundary between the South American and Caribbean plates.[7]

Geology

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Mountains with snowy peaks
Aerial view of Valle Carbajal in the Tierra del Fuego. The Andes range is about 200 km (124 mi) wide throughout its length, except in the Bolivian flexure where it is about 640 kilometres (398 mi) wide.

The Andes are an orogenic belt of mountains along the Pacific Ring of Fire, a zone of volcanic activity that encompasses the Pacific rim of the Americas as well as the Asia-Pacific region. The Andes are the result of tectonic plate processes extending during the Mesozoic and Tertiary eras, caused by the subduction of oceanic crust beneath the South American Plate as the Nazca Plate and South American Plate converge. These processes were accelerated by the effects of climate. As the uplift of the Andes created a rain shadow on the western fringes of Chile, ocean currents and prevailing winds carried moisture away from the Chilean coast. This caused some areas of the subduction zone to be sediment-starved, which in turn prevented the subducting plate from having a well lubricated surface. These factors increased the rate of contractional coastal uplift in the Andes.[8] The main cause of the rise of the Andes is the contraction of the western rim of the South American Plate due to the subduction of the Nazca Plate and the Antarctic Plate. To the east, the Andes range is bounded by several sedimentary basins, such as the Orinoco Basin, the Amazon Basin, the Madre de Dios Basin, and the Gran Chaco, that separate the Andes from the ancient cratons in eastern South America. In the south, the Andes share a long boundary with the former Patagonia Terrane. To the west, the Andes end at the Pacific Ocean, although the Peru–Chile Trench can be considered their ultimate western limit.

"Cono de Arita" in the Puna de Atacama, Salta (Argentina)

The Andean orogen has a series of bends or oroclines. The Bolivian Orocline is a seaward-concave bending in the coast of South America and the Andes Mountains at about 18° S.[9][10] At this point, the orientation of the Andes turns from northwest in Peru to south in Chile and Argentina.[10] The Andean segments north and south of the Orocline have been rotated 15° counter-clockwise to 20° clockwise respectively.[10][11] The Bolivian Orocline area overlaps with the area of the maximum width of the Altiplano Plateau, and according to Isacks (1988) the Orocline is related to crustal shortening.[9] The specific point at 18° S where the coastline bends is known as the Arica Elbow.[12] Further south lies the Maipo Orocline, a more subtle orocline between 30° S and 38°S with a seaward-concave break in the trend at 33° S.[13] Near the southern tip of the Andes lies the Patagonian Orocline.[14]

Orogeny

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Mururata and Illimani in Bolivia, two prominent peaks formed by the tectonic uplift caused by the Andean orogeny and plate subduction.

The western rim of the South American Plate has been the place of several pre-Andean orogenies since at least the late Proterozoic and early Paleozoic, when several terranes and microcontinents collided and amalgamated with the ancient cratons of eastern South America, by then the South American part of Gondwana.

The formation of the modern Andes began with the events of the Triassic, when Pangaea began the breakup that resulted in developing several rifts. The development continued through 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 constant, as different regions have had different degrees of tectonic stress, uplift, and erosion.

Across the 1,000-kilometer-wide (620 mi) 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 far east regions of the Andes experience a series of changes resulting from the Andean orogeny. Parts of the Sunsás Orogen in Amazonian craton disappeared from the surface of the earth, being overridden by the Andes.[15] The Sierras de Córdoba, where the effects of the ancient Pampean orogeny can be observed, owe their modern uplift and relief to the Andean orogeny in the Tertiary.[16] Further south in southern Patagonia, the onset of the Andean orogeny caused the Magallanes Basin to evolve from being an extensional back-arc basin in the Mesozoic to being a contractional foreland basin in the Cenozoic.[17]

Seismic activity

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Tectonic forces above 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. Many high-magnitude earthquakes have been recorded in the region, such as the 2010 Maule earthquake (M8.8), the 2015 Illapel earthquake (M8.2), and the 1960 Valdivia earthquake (M9.5), which as of 2024 was the strongest ever recorded on seismometers.

The amount, magnitude, and type of seismic activity varies greatly along the subduction zone. These differences are due to a wide range of factors, including friction between the plates, angle of subduction, buoyancy of the subducting plate, rate of subduction, and hydration value of the mantle material. The highest rate of seismic activity is observed in the central portion of the boundary, between 33°S and 35°S. In this area, the angle of subduction is very low, meaning the subducting plate is nearly horizontal. Studies of mantle hydration across the subduction zone have shown a correlation between increased material hydration and lower-magnitude, more frequent seismic activity. Zones exhibiting dehydration instead are thought to have a higher potential for larger, high-magnitude earthquakes in the future.[18]

The mountain range is also a source of shallow intraplate earthquakes within the South American Plate. The largest such earthquake (as of 2024) struck Peru in 1947 and measured Ms  7.5. In the Peruvian Andes, these earthquakes display normal (1946), strike-slip (1976), and reverse (1969, 1983) mechanisms. The Amazonian Craton is actively underthrusted beneath the sub-Andes region of Peru, producing thrust faults.[19] In Colombia, Ecuador, and Peru, thrust faulting occurs along the sub-Andes due in response to contraction brought on by subduction, while in the high Andes, normal faulting occurs in response to gravitational forces.[20]

In the extreme south, a major transform fault separates Tierra del Fuego from the small Scotia Plate.

Volcanism

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Sol de Mañana, an area of intense geothermal activity with fumaroles and geysers, Bolivia
This photo from the ISS shows 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 distributed in four volcanic zones separated by areas of inactivity. The Andean volcanism is a result of the subduction of the Nazca Plate and Antarctic Plate underneath the South American Plate. The belt is subdivided into four main volcanic zones that are separated from each other by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products, and morphology.[21] Although some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences inside volcanic zones and even between neighboring volcanoes. Despite being a typical location for calc-alkalic and subduction volcanism, the Andean Volcanic Belt has a large range of volcano-tectonic settings, such as rift systems, extensional zones, transpressional faults, subduction of mid-ocean ridges, and seamount chains apart from a large range of crustal thicknesses and magma ascent paths, and different amount of crustal assimilations.

Ore deposits and evaporites

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The Andes Mountains host large ore and salt deposits, and some of their eastern fold and thrust belts act as traps for commercially exploitable amounts of hydrocarbons. In the forelands of the Atacama Desert, some of the largest porphyry copper mineralizations occur, making Chile and Peru the first- and second-largest exporters of copper in the world.[22][23] Porphyry copper in the western slopes of the Andes has been generated by hydrothermal fluids (mostly water) during the cooling of plutons or volcanic systems. The porphyry mineralization further benefited from the dry climate that reduced the disturbing actions of meteoric water. The dry climate in the central western Andes has also led to the creation of extensive saltpeter deposits that were extensively mined until the invention of synthetic nitrates. Yet another result of the dry climate are the salars of Atacama and Uyuni, the former being the largest source of lithium and the latter the world's largest reserve of the element.[citation needed] Early Mesozoic and Neogene plutonism in Bolivia's Cordillera Central created the Bolivian tin belt as well as the famous, now mostly depleted, silver deposits of Cerro Rico de Potosí.

Climate

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The Andes Mountains is connected to the climate of South America, particularly through the hyper-arid conditions of the adjacent Atacama Desert. The Atacama Bench, a prominent low-relief feature along the Pacific seaboard, serves as a key geomorphological record of the long-term interplay between Andean tectonics and Cenozoic climate. While the initial uplift and shortening of the Andes were driven by the subduction of the Nazca Plate beneath the South American Plate, arid climate acted as an important feedback mechanism. Reduced erosion rates in the increasingly arid Atacama region may have effectively stopped tectonic activity in certain parts of the mountain range. This lack of erosion could have facilitated the eastward propagation of deformation, leading to the widening of the Andean orogen over time. Thus, the Atacama Desert and its geological features, like the Atacama Bench, offer critical insights into the coupled evolution of the Andes Mountains and the changing regional climate.[24]

History

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The Andes Mountains, initially inhabited by hunter-gatherers, experienced the development of agriculture and the rise of politically centralized civilizations, which culminated in the establishment of the century-long Inca Empire. This all changed in the 16th century, when the Spanish conquistadors colonized the mountains in advance of the mining economy.

In the tide of anti-imperialist nationalism, the Andes became the scene of a series of independence wars in the 19th century, when rebel forces swept through the region to overthrow Spanish colonial rule. Since then, many former Spanish territories have become five independent Andean states.

Climate and hydrology

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Central Andes
Bolivian Andes

The climate in the Andes varies greatly depending on latitude, altitude, and proximity to the sea. Temperature, atmospheric pressure, and humidity decrease in higher elevations. The southern section is rainy and cool, while the central section is 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 kilometers away from the snow-covered peak of Cotopaxi. The mountains have a large effect on the temperatures of nearby areas. The snow line depends on the location. It is between 4,500 and 4,800 m (14,800 and 15,700 ft) in the tropical Ecuadorian, Colombian, Venezuelan, and northern Peruvian Andes, rising to 4,800–5,200 m (15,700–17,100 ft) in the drier mountains of southern Peru and northern Chile south to about 30°S before 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.[25]

The Andes of Chile and Argentina can be divided into two climatic and glaciological zones: the Dry Andes and the Wet Andes. Since the Dry Andes extend from the latitudes of the Atacama Desert to the area of the Maule River, precipitation is more sporadic, 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.

In the high Andes of Central Chile and Mendoza Province, rock glaciers are larger and more common than glaciers; this is due to the high exposure to solar radiation.[26] In these regions, glaciers occur typically at higher altitudes than rock glaciers.[27] The lowest active rock glaciers occur at 900 m a.s.l. in Aconcagua.[27]

The Yungas region between Bolivia and Peru, part of the tropical andes

Though precipitation increases with height, there are semiarid conditions in the nearly 7,000-metre (22,966 ft) highest mountains of the Andes. This dry steppe climate is considered to be typical of the subtropical position at 32–34° S. The valley bottoms have no woods, just dwarf scrub. The largest glaciers, for example the Plomo Glacier and the Horcones Glaciers, do not even reach 10 km (6.2 mi) in length and have only insignificant ice thickness. At glacial times, however, c. 20,000 years ago, the glaciers were over ten times longer. On the east side of this section of the Mendozina Andes, they flowed down to 2,060 m (6,760 ft) and on the west side to about 1,220 m (4,000 ft) above sea level.[28][29] The massifs of Aconcagua (6,961 m or 22,838 ft), Tupungato (6,550 m or 21,490 ft), and Nevado Juncal (6,110 m or 20,050 ft) are tens of kilometres away from each other and were connected by a joint ice stream network. The Andes' dendritic glacier arms, components of valley glaciers, were up to 112.5 km (69.9 mi) long and over 1,250 m (4,100 ft) thick, and spanned a vertical distance of 5,150 m (16,900 ft). The climatic glacier snowline (ELA) was lowered from 4,600 m (15,100 ft) to 3,200 m (10,500 ft) at glacial times.[28][30]

Flora

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Laguna de Sonso tropical dry forest in Northern Andes

The Andean region cuts across several natural and floristic regions, due to its extension, from Caribbean Venezuela to cold, windy, and wet Cape Horn passing through the hyperarid Atacama Desert. Rainforests and tropical dry forests[31] used to[when?] encircle much of the northern Andes but are now greatly diminished, especially in the Chocó and inter-Andean valleys of Colombia. Opposite 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.[32] The small tree Cinchona pubescens, a source of quinine that 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 that began during the Incan period. Regardless, in modern times, the clearance has accelerated, and the trees are now considered highly endangered, with some believing that as little as 10% of the original woodland remains.[33]

Fauna

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A male Andean cock-of-the-rock, a species found in humid Andean forests and the national bird of Peru
Herds of llamas in the Bolivian Andes

The Andes are rich in fauna: With almost 1,000 species, of which roughly 2/3 are endemic to the region, the Andes are the most important region in the world for amphibians.[32] The diversity of animals in the Andes is high, with almost 600 species of mammals (13% endemic), more than 1,700 species of birds (about 1/3 endemic), more than 600 species of reptiles (about 45% endemic), and almost 400 species of fish (about 1/3 endemic).[32]

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 crepuscular (active during dawn and dusk) chinchillas, two threatened members of the rodent order, inhabit the Andes' alpine regions.[34][35] 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.[36] Other animals found in the relatively open habitats of the high Andes include the huemul, cougar, foxes in the genus Pseudalopex,[34][35] 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.[36]

Lake Titicaca hosts several endemics, among them the highly endangered Titicaca flightless grebe[36] and Titicaca water frog.[37] 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.[36] These forest-types, which includes the Yungas and parts of the Chocó, are very rich in flora and fauna, although few large mammals exist, exceptions being the threatened mountain tapir, spectacled bear, and yellow-tailed woolly monkey.[34]

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 are commonly seen—in contrast to several vocal but typically cryptic species of wrens, tapaculos, and antpittas.[36]

A number of species such as the royal cinclodes and white-browed tit-spinetail are associated with Polylepis, and consequently also threatened.[36]

Human activity

[edit]

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.[38] The government sponsored the construction of aqueducts and roads in addition to pre-existing installations. Some of these constructions still exist today.

Frederic Edwin Church, Heart of the Andes, 1859.

Devastated by European diseases and by civil war, the Incas were defeated in 1532 by an alliance composed of tens of thousands of 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.

Cities

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In modern times, the largest cities in the Andes are Bogotá, with a metropolitan population of over ten million, and Santiago, Medellín, Cali, and Quito. Lima is a coastal city adjacent to the Andes and is the largest city of all Andean countries. It is the seat of the Andean Community of Nations.

La Paz, Bolivia's seat of government, is the highest capital city in the world, at an elevation of approximately 3,650 m (11,975 ft). Parts of the La Paz conurbation, including the city of El Alto, extend up to 4,200 m (13,780 ft).

Other cities in or near the Andes include Bariloche, Catamarca, Jujuy, Mendoza, Salta, San Juan, Tucumán, and Ushuaia in Argentina; Calama and Rancagua in Chile; Cochabamba, Oruro, Potosí, Sucre, Tarija, and Yacuiba in Bolivia; Arequipa, Cajamarca, Cusco, Huancayo, Huánuco, Huaraz, Juliaca, and Puno in Peru; Ambato, Cuenca, Ibarra, Latacunga, Loja, Riobamba, and Tulcán in Ecuador; Armenia, Cúcuta, Bucaramanga, Duitama, Ibagué, Ipiales, Manizales, Palmira, Pasto, Pereira, Popayán, Rionegro, Sogamoso, Tunja, and Villavicencio in Colombia; and Barquisimeto, La Grita, Mérida, San Cristóbal, Tovar, Trujillo, and Valera in Venezuela. The cities of Caracas, Valencia, and Maracay are in the Venezuelan Coastal Range, which is a debatable extension of the Andes at the northern extremity of South America.

Transportation

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Cities and large towns are connected with asphalt-paved roads, while smaller towns are often connected by dirt roads, which may require a four-wheel-drive vehicle.[39]

The rough terrain has historically put the costs of building highways and railroads that cross the Andes out of reach of most neighboring countries, even with modern civil engineering practices. For example, the main crossover of the Andes between Argentina and Chile is still accomplished through the Paso Internacional Los Libertadores. Only recently[when?] have the ends of some highways that came rather close to one another from the east and the west been connected.[40] Much of the transportation of passengers is done via aircraft.

There is one railroad that connects Chile with Peru via the Andes, however, and there are others that make the same connection via southern Bolivia.

There are multiple highways in Bolivia that cross the Andes. Some of these were built during a period of war between Bolivia and Paraguay, in order to transport Bolivian troops and their supplies to the war front in the lowlands of southeastern Bolivia and western Paraguay.

For decades, Chile claimed ownership of land on the eastern side of the Andes. These claims were given up in about 1870 during the War of the Pacific between Chile and the allied Bolivia and Peru, in a diplomatic deal to keep Peru out of the war. The Chilean Army and Chilean Navy defeated the combined forces of Bolivia and Peru, and Chile took over Bolivia's only province on the Pacific Coast, some land from Peru that was returned to Peru decades later. Bolivia has been completely landlocked ever since. It mostly uses seaports in eastern Argentina and Uruguay for international trade because its diplomatic relations with Chile have been suspended since 1978.

Because of the tortuous terrain in places, villages and towns in the mountains—to which travel via motorized vehicles is of little use—are still located in the high Andes of Chile, Bolivia, Peru, and Ecuador. Locally, the relatives of the camel, the llama, and the alpaca continue to carry out important uses as pack animals, but this use has generally diminished in modern times. Donkeys, mules, and horses are also useful.

Agriculture

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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, and was used for the production of chicha, important to Andean native people. Currently,[when?] tobacco, cotton, quinoa, and coffee are the main export crops. Coca, despite eradication programs in some countries, remains an important crop for legal local use in a mildly stimulating herbal tea, and illegally for the production of cocaine.

Irrigation

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A quinoa field in the Bolivian altiplano

In unirrigated land, pasture is the most common type of land use. In the rainy season (summer), part of the rangeland is used for cropping (mainly potatoes, barley, broad beans, and wheat).

Irrigation is helpful in advancing the sowing data of the summer crops, which guarantees an early yield in periods of food shortage. Also, by early sowing, maize can be cultivated higher up in the mountains (up to 3,800 m (12,500 ft)). In addition, it makes cropping in the dry season (winter) possible and allows the cultivation of frost-resistant vegetable crops like onion and carrot.[41]

Mining

[edit]
Chilean huasos, 19th century

The Andes rose to fame for their 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 on a large scale after the Spanish arrival. Potosí in present-day Bolivia and Cerro de Pasco in Peru were among the principal mines of the Spanish Empire in the New World. Río de la Plata and Argentina[42] derive their names from the silver of Potosí.

Currently, mining in the Andes of Chile and Peru places these countries as the first and second major producers of copper in the world. Peru also contains the 4th-largest goldmine in the world: the Yanacocha. The Bolivian Andes principally produce tin, although historically silver mining had a huge impact on the economy of 17th-century Europe.[citation needed] In Chile in the higher portions of the Andes there are only mining districs dominated by large-scale mining, while medium and small-scale mining is more common at lower altitudes.[43] For mines in the high Andes there are logistical difficulties in the use of sea water, in addition to increased probabilities of extreme weather events that may disrupt water supply.[44] The gold deposits of the El Indio Gold Belt tend to lie along the Argentina–Chile border and next to or below glaciers and gold mining there have thus issues relating to the bi-nationality and their environmental impacts on glaciers.[45]

Mining in the cold conditions in the Andes pose also difficult conditions for outdoor workers such as pallaqueras and for the batteries of electrified machinery.[46][47]

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 important. The Andes have a vast supply of lithium; Argentina, Bolivia, and Chile have the three largest reserves in the world respectively.[48]

Peaks

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

Argentina

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The Aconcagua, Argentina, the highest mountain in the Americas

The border between Argentina and Chile

[edit]
Fitz Roy in the Patagonia region between Argentina and Chile
Huayna Potosí, Bolivia

Bolivia

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Sajama, Bolivia
Kunturiri, Bolivia

The border between Bolivia and Chile

[edit]
Parinacota, Bolivia/Chile

Chile

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View of Cuernos del Paine in Torres del Paine National Park, Chile

Colombia

[edit]
Nevado del Huila, Colombia

Ecuador

[edit]
Chimborazo near Riobamba, Ecuador

Peru

[edit]
Huandoy, Peru
Alpamayo, Peru

Venezuela

[edit]
Pico Humboldt, Venezuela

See also

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Notes

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References

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Bibliography

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The Andes form the longest continental on , extending more than 7,000 kilometers along the western margin of from in the north to in the south, traversing seven countries including , , , , , and . The range's highest peak is in , reaching 6,961 meters above . Formed primarily through the ongoing subduction of the oceanic Nazca Plate beneath the continental South American Plate, the Andes exhibit active tectonic processes that generate frequent earthquakes, volcanic activity, and continued crustal uplift. This geodynamic setting has produced a diverse array of physiographic features, from glaciated peaks and high plateaus to deep valleys and coastal cordilleras, influencing regional climates, , and hotspots such as the , which harbor exceptional despite the harsh alpine conditions. The range's resources, including minerals and water, have driven and economic activities, though seismic hazards and erosion pose ongoing challenges to infrastructure and ecosystems.

Etymology

Origin of the Name

The etymology of "Andes" derives primarily from Quechua, the of the , with the most accepted origin tracing to the term anti, signifying "east" and referring to , the eastern quarter of the Inca domain relative to . This usage reflected the mountains' position as the eastern boundary for Andean highland peoples. An alternative interpretation links anti or a related form andi to "high crest," evoking the range's elevated ridges. Spanish explorers adopted the name in the mid-16th century, with one of the earliest documented European references appearing in Pedro Cieza de León's Crónica del Perú (published 1553), where he describes the "sierra" or known locally as Andes. Indigenous variations persist in related languages; for instance, Aymara speakers in the southern highlands may connect it to anta or amta, terms denoting "," possibly nodding to the region's abundant deposits visible in oxidized outcrops. In Mapudungun, spoken by southern groups like the , no direct exists for the standardized "Andes," as the term's dissemination northward aligned with Quechua's imperial reach rather than localized southern .

Physical Geography

Location and Extent

The Andes constitute the longest continental above , extending approximately 7,600 kilometers from north to south along the western margin of . This chain parallels the coastline, forming a continuous barrier that influences across multiple latitudes. The northern terminus lies in western Venezuela, near the Colombian border, while the southern end reaches at the tip of the continent, where the range integrates with island arcs extending into the Atlantic and Pacific. The Andes traverse seven countries: , , , , , , and , with the range serving as a natural boundary between and over much of its length. In width, the Andes vary from 200 kilometers in narrower northern and southern segments to up to 700 kilometers in the central portions, particularly between 18°S and 20°S where the broadest expanses occur. The across the range stands at approximately 4,000 meters, though this encompasses diverse topographic zones from coastal to high plateaus.

Topography and Major Features

The Andes form the longest continental mountain range in the world, extending approximately 5,000 km along the western edge of from to . The range varies in width from 200 to 700 km, with its broadest section in the Central Andes reaching up to 700 km, while narrower segments occur in the Northern Andes at 400–450 km. Average elevations across the chain hover around 4,000 m, though individual peaks exceed this significantly. Structurally, the Andes divide into Northern, Central, and Southern segments, each exhibiting distinct topographic profiles. The Northern Andes, spanning , , and , feature a complex arrangement of parallel cordilleras separated by intermontane basins and valleys, contributing to a rugged terrain with elevations typically between 2,500 and 4,000 m in plateau regions. In contrast, the Central Andes of and host expansive high plateaus, including the , a vast intermontane basin averaging 3,750 m in elevation and covering hundreds of kilometers as the second-largest such plateau globally after . The Southern Andes, through and , narrow in places but include glaciated highlands and the , an arid plateau extending about 320 km north-south at elevations around 4,000–4,500 m, characterized by salt flats and desolate tablelands. Prominent features include the Patagonian ice fields in the southernmost Andes, comprising the Northern Patagonian Icefield (approximately 3,976 km²) and the larger Southern Patagonian Icefield (13,219 km²), which together form the largest non-polar ice masses outside , spanning the Chile-Argentina border atop peaks exceeding 3,000 m. Intermontane basins, such as those in the Puna and , trap sediment and create enclosed depressions amid the cordilleras, influencing local . Major river systems originate from Andean headwaters, including the from the Peruvian Andes and the from the Colombian-Venezuelan highlands, draining eastward into vast basins.

Geology

Tectonic Orogeny

The Andes mountain range primarily results from the ongoing of the oceanic Nazca Plate beneath the continental South American Plate, a process that generates compressional forces leading to crustal shortening, thickening, and subsequent isostatic uplift. This convergence occurs at rates varying from approximately 70 mm/year in the north to 80 mm/year in the south, with the denser Nazca descending into along the Peru-Chile Trench, inducing thrusting and folding in the overriding South American crust. The subduction angle shallows northward, influencing the distribution of deformation, while slab rollback and trench retreat at rates up to 2 cm/year contribute to arc magmatism and back-arc spreading in localized segments. The Andean orogeny unfolded in multiple pulses tied to changes in dynamics, plate motion, and inherited crustal weaknesses. The Incaic phase, centered in the Eocene (circa 50-35 million years ago), involved initial shortening and uplift in northern and central segments, driven by accelerated convergence following the breakup of . This was followed by the Quechua phases in the (approximately 25-5 million years ago), marked by widespread thrusting, basin inversion, and crustal thickening exceeding 70 km in the Altiplano-Puna plateau, as rates increased and flat-slab segments temporarily stalled rollback. Modern uplift accelerated since the (about 5 million years ago), linked to renewed steepening of the slab and of overthickened lower crust, elevating the range to average heights over 4 km. Contemporary geodetic observations confirm active deformation, with GPS data revealing uplift rates of 5-10 mm/year across parts of the central Andes , attributable to ongoing at 10-15 mm/year and viscous lower-crustal flow. These rates vary regionally, with higher values in the southern Andes influenced by combined tectonic and post-glacial isostatic adjustment, underscoring the persistence of subduction-driven orogenesis.

Seismic Activity

The Andean seismic activity is primarily driven by the oblique of the Nazca Plate beneath the South American Plate along a ~7,000 km megathrust interface, which accommodates convergence at rates of 6-8 cm/year and generates frequent thrust earthquakes with magnitudes exceeding 8.0. This interface exhibits heterogeneous locking, with seismic gaps prone to rupture, as evidenced by post-2000 events including the 2001 Mw 8.4 and 2007 Mw 8.0 earthquakes in . The most powerful recorded earthquake, the 1960 Valdivia event (Mw 9.5), ruptured ~1,000 km of the southern Chile megathrust on May 22, 1960, with an at 38.24°S, 73.05°W, triggering a trans-Pacific that caused over 2,000 deaths regionally and additional fatalities in , , and the . The 2010 Maule earthquake (Mw 8.8) on February 27 struck , rupturing ~650 km bilaterally from ~34°S to 38°S along the zone, with slip concentrated in asperities locked since prior events, resulting in ~500 deaths and widespread infrastructure damage. Intraplate seismicity contributes significantly, with intermediate-depth earthquakes (60-300 km) occurring within the subducting slab due to mechanisms such as embrittlement and thermal shear instabilities, concentrated in double seismic zones beneath and northern . These events, often reaching Mw 7+, contrast with shallower crustal quakes along back-arc faults, which reflect compressional stresses from slab anchoring. Recent advancements in seismic monitoring include finite-frequency P-wave models revealing slab geometry variations, such as the Pampean flat-slab segment (27°-33°S) where aseismic underthrusting and low-angle suppress typical arc but enhance intraslab events imaged as high-velocity anomalies to ~400 km depth. These 2023-2025 studies integrate teleseismic data from regional networks to map locking patterns and hydration states, informing probabilistic hazard models amid ongoing convergence.

Volcanism

The Andean Volcanic Belt features over 200 volcanoes, reflecting subduction-driven magmatism where fluids from the dehydrating Nazca Plate trigger in the mantle wedge, generating magmas that ascend to form stratovolcanoes and calderas. This process concentrates volcanism along discrete segments, with the Central Volcanic Zone (spanning southern , , northern , and ) hosting 62 potentially active edifices amid thick that promotes explosive behaviors through differentiation and volatile retention. Eruption styles vary from effusive to highly explosive, influenced by magma composition and ascent dynamics; Llaima in exemplifies basaltic-andesitic effusive activity with frequent Strombolian explosions and lava flows, as seen in its 2007-2009 and 2021 events producing kilometers-long flows. In contrast, in produced a VEI 6 in February 1600, ejecting ~13 km³ of material and generating sustained columns up to 35 km high, the largest historical event in the Andes due to rapid decompression of gas-rich andesitic . Ongoing activity underscores persistent hazards; Sabancaya in entered unrest in 2013 with magnitude >4.5 earthquakes, transitioning to Vulcanian explosions from 2016 with daily ash plumes up to 4 km and thermal anomalies persisting through 2021. In 2025, Uturuncu in —a dormant complex inactive for over 250,000 years—exhibited continued "zombie-like" unrest via seismic swarms (1,700 microearthquakes analyzed) and gas emissions, linked to rather than imminent intrusion, with deformation patterns indicating low eruption probability despite subsurface fluid movement. These observations highlight monitoring needs, as crustal thickness and slab modulate eruption triggers across the arc.

Mineral Deposits

The mineral deposits of the Andes primarily result from subduction-related arc magmatism, where fluids derived from the dehydrating Nazca plate flux of wedge, generating hydrous, metal-enriched magmas that ascend and release hydrothermal fluids to concentrate ores through in fractures and intrusions. These processes, active since the but peaking in the , link mineralization to episodes of crustal thickening and shallowing angles that enhance fluid circulation and metal solubility. Porphyry copper-gold deposits dominate the central Andean metallogenic belt, particularly in northern and southern , formed by to oxidized calc-alkaline magmas that exsolve saline fluids precipitating , , and native in stockwork veinlets within dioritic porphyries. Examples include the Paleocene-Eocene Toquepala and Cuajone systems in , hosted in andesitic volcanics, and Chile's Eocene-Oligocene deposits like , which contain billions of tonnes of copper ore disseminated in altered host rocks. In Bolivia's Eastern Cordillera, the Bolivian tin belt features greisen- and vein-type deposits of associated with late Oligocene-Miocene S-type granites, where post-magmatic hydrothermal fluids mobilized tin from crustal sources during tectonic compression and crustal melting. These polymetallic systems, spanning over 1,000 km, include major occurrences at Llallagua and Huanuni, with combined Bolivian-Peruvian tin reserves estimated at 550,000 tonnes as of 2022. The exemplifies silver-tin vein deposits in the tin belt, formed in dacitic ignimbrites via boiling hydrothermal fluids that deposited argentite, , and in fault-hosted veins during episodic linked to dynamics; discovered in , it retains over 500 million s of polymetallic reserves grading several percent tin and grams per silver. Evaporitic salars on the Andean Altiplano, such as Bolivia's , host lithium-rich brines accumulated through evaporation of closed-basin lakes fed by volcanic and hydrothermal inputs, concentrating from of surrounding ignimbrites and sediments; alone contains an estimated 21 million tonnes of resources in halite-hosted brines beneath the .

Climate and Hydrology

Climatic Variations

The Andes exhibit pronounced climatic variations driven by latitude, with northern sectors dominated by tropical wet conditions, central regions by extreme aridity, and southern areas by cold temperate regimes. In the northern Andes (approximately 10°N to 0°S), encompassing , , and northern , humid tropical climates prevail, with annual often exceeding 2,000 mm on eastern slopes due to moisture advection from the and orographic enhancement. Central latitudes (roughly 0°S to 30°S), particularly along the Peru-Chile border, feature hyper-arid conditions in the , where core areas receive less than 5 mm of annual , resulting from persistent in the southeastern Pacific subtropical anticyclone and a strong from the Andean barrier blocking easterly moisture. Southern Andes (south of 30°S) transition to cooler temperate climates influenced by westerly storm tracks, yielding higher precipitation—up to 3,000 mm annually on windward Chilean slopes—contrasting sharply with leeward Patagonian aridity. Altitudinal zonation overlays these latitudinal patterns, creating vertical climate bands through adiabatic lapse rates of approximately 6.5°C per 1,000 m elevation gain. In tropical northern Andes, the tierra caliente zone ( to ~1,000 m) maintains hot, humid conditions with mean temperatures above 24°C and dense . The succeeding tierra templada (1,000–2,500 m) cools to 18–24°C, supporting subtropical crops amid frequent . Higher tierra fría (2,500–3,500 m) features means of 10–18°C, suitable for hardy tubers, while grasslands (3,500–4,500 m) endure frost-prone conditions with sparse, tussocky before the nival zone above ~4,800 m, where perpetual ice dominates and temperatures drop below 0°C year-round. In arid central sectors, these zones compress and desiccate, with minimal amplifying temperature extremes; southern temperate latitudes shift equivalents to subalpine meadows under cooler baselines.

Water Resources and Glacier Dynamics

The glaciers of the Andes function as natural reservoirs within the regional hydrological cycle, accumulating primarily during the and releasing during drier periods to sustain discharges. This buffering effect is vital for downstream ecosystems and human uses, including , potable , and hydroelectric , particularly in basins like the Amazon, Paraná, and Pacific coastal rivers. In the , glacial contributions can account for up to 50% of dry-season in some catchments, mitigating seasonal variability driven by monsoon-like regimes and El Niño-Southern Oscillation influences. ![Aconcagua south wall with snow][float-right]
Andean glaciers currently span an estimated total area of approximately 25,000 km² across latitudes from to and , though precise inventories vary due to remote terrain and differing methodologies in satellite-based assessments. In the tropical segment (roughly 10°N to 23°S), which holds smaller but critical ice masses, glaciers have undergone significant retreat, losing 30-50% of their volume since the , with accelerated thinning rates of 0.5-1 meter per year in recent decades as measured by altimetry and geodetic surveys. This mass loss equates to an average rate of -0.5 to -1.0 Gt yr⁻¹ for tropical glaciers from 2000-2018, reflecting cumulative negative balances where exceeds accumulation.
Historical glacier dynamics reveal substantial natural variability, independent of anthropogenic influences. During the stadial (approximately 12,900-11,700 years before present), tropical Andean glaciers advanced markedly, extending equilibrium lines by hundreds of meters, as evidenced by dating of moraines and paleoprecipitation proxies indicating enhanced snowfall from southward shifts in the rather than solely colder temperatures. Such episodes underscore precipitation's dominant role in at lower latitudes, contrasting with temperature-driven in higher-elevation or polar settings. In the , glaciers reached minima during warmer intervals like the current but exhibited readvances tied to regional moisture fluctuations, highlighting that retreat phases are not unprecedented but current rates in the exceed those post-Little Ice Age based on multi-proxy reconstructions. Contemporary trends show latitudinal heterogeneity: tropical glaciers exhibit near-uniform negative balances with 40-60% area reductions since 1980 in and , while Patagonian outlets display variable responses, including localized thickening from increased in some southern sectors offsetting melt. Overall Andean mass loss has intensified since the , with empirical data from GRACE gravimetry and ICESat altimetry confirming domain-wide thinning but emphasizing local factors like debris cover and supraglacial lakes accelerating in non-calving systems. These dynamics sustain water for 70-90 million residents in Andean nations, though peak melt contributions may shift toward earlier seasons, altering hydrological regimes without implying total given underlying and rainfall dependencies.

Biodiversity

Flora and Vegetation Zones

In the northern Andes, encompassing regions from Venezuela to Ecuador at elevations typically above 3,500 meters, grasslands prevail as a high-altitudinal characterized by tussock-forming grasses (e.g., spp.), cushion plants, and giant rosette species like and Puya, which form dense, low-stature vegetation adapted to intense solar radiation, frequent frosts, and nutrient-poor soils. These formations exhibit physiological adaptations including succulent leaves, dense trichomes for insulation, and in some taxa to minimize under diurnal fluctuations exceeding 20°C. Transitioning southward into the central Andes of and , puna grasslands occupy similar high-elevation belts between 3,800 and 5,000 meters, dominated by bunchgrasses such as and Stipa species alongside scattered shrubs like Baccharis and Adesmia, forming open, windswept meadows on volcanic and glacial substrates with seasonal under 500 mm annually. Vegetation here shows resilience to herbivory and through rhizomatous growth and deep systems penetrating up to 2 meters into permafrost-affected soils. In the southern Andes of Chile and Argentina, latitudinal shifts yield Valdivian temperate forests below 1,000 meters, featuring evergreen broadleaf trees like Nothofagus obliqua and Eucryphia cordifolia in humid, coastal-influenced zones receiving over 2,000 mm of annual rainfall, with understories of ferns and bamboos (Chusquea spp.) supporting multilayered canopies up to 40 meters tall. Arid western slopes and intermontane basins, conversely, host sclerophyllous shrublands with drought-deciduous species such as Prosopis tamarugo and Geoffroea decorticans, featuring small, leathery leaves and resinous coatings to conserve water in hyper-arid conditions where mean annual precipitation falls below 100 mm. Across these zones, in vascular reaches exceptionally high levels, estimated at 15-25% in high-Andean habitats due to orographic isolation and microclimatic fragmentation, with the harboring over 15,000 , many restricted to specific elevational bands.

Fauna and Endemic Species

The supports a diverse array of adapted to high-altitude conditions, including approximately 600 mammal and over 1,700 bird , with many exhibiting physiological adaptations such as enhanced oxygen-binding hemoglobin variants to cope with hypoxia at elevations exceeding 4,000 meters. The region's faunal richness stems from its steep elevational gradients and varied microhabitats, fostering specialized niches that promote , particularly among vertebrates in the portion spanning to . Among mammals, high-altitude camelids predominate, including the (Vicugna vicugna) and (Lama guanicoe), both endemic to the Andes and capable of thriving above 4,500 meters due to cardiovascular adaptations like oversized hearts—up to 20% larger relative to body size in guanacos—to maintain blood oxygenation in rarefied air. The (Tremarctos ornatus), South America's sole native bear and fully endemic to Andean slopes, features a stocky build, stance, and facial markings suited for arboreal foraging in montane forests up to 4,200 meters, where it consumes over 90% plant matter. These exemplify evolutionary responses to altitudinal stressors, with genetic studies confirming hypoxia tolerance via upregulated genes for production. Avian fauna includes the Andean condor (Vultur gryphus), the largest flying land bird with a wingspan reaching 3 meters, enabling efficient thermal soaring over vast Andean expanses at altitudes up to 5,500 meters despite low air density. Approximately one-third of the 1,700+ bird species in the region are endemic, concentrated in hotspots like the eastern Andean slopes of and , where isolated valleys harbor unique assemblages vulnerable to natural habitat fragmentation that influences population dynamics through predation and dispersal limits rather than solely anthropogenic factors. Other notable endemics include the mountain tapir (Tapirus pinchaque), restricted to paramo ecosystems above 2,000 meters, underscoring the Andes' role as a global center for vertebrate diversification driven by orographic isolation.

Human History

Pre-Columbian Civilizations

The earliest complex societies in the Andes developed in the Norte Chico region of coastal , with the Caral-Supe civilization flourishing between approximately 3500 and 1800 BCE. This culture constructed monumental architecture, including large platform mounds and sunken plazas, without reliance on ceramics or defensive structures, indicating a focus on cooperative labor for rather than warfare. Sites like featured over 30 settlements with radiocarbon dates confirming occupation from 3100 to 1800 BCE, supported by agriculture of and squash alongside . Following the decline of Norte Chico, the emerged around 900 BCE in the northern Andean highlands, centered at , and persisted until about 200 BCE. This society unified diverse regional groups through religious influence, evidenced by standardized iconography in stone carvings and textiles depicting jaguars and supernatural beings. Achievements included advanced stone , underground galleries for ritual use, and early in gold and , which spread influence across . Population growth led to urban settlements and specialized crafts like by 400-200 BCE. Subsequent regional civilizations arose during the Early Intermediate Period (c. 200 BCE-600 CE), including the Moche in northern (c. 100-800 CE) and in the south (c. 100 BCE-800 CE). The Moche built adobe pyramids such as the , which reached 41 meters high using over 100 million bricks, and developed sophisticated canals extending into deserts. is noted for its massive geoglyphs, including the Nazca Lines covering 450 square kilometers, likely used for ritual water ceremonies, alongside polychrome pottery and underground aqueducts () that remain functional. Terrace began expanding in these periods to maximize steep Andean slopes, enhancing crop yields of potatoes, , and through soil retention and control. The Middle Horizon (c. 600-1000 CE) saw the rise of expansive states like Wari in central and near , precursors to imperial administration. Wari constructed a road network spanning hundreds of kilometers and planned cities with rectangular enclosures, while featured the monolith and raised fields (sukakollos) for flood-resistant farming. advanced with arsenic bronze tools and ornaments, reflecting specialized workshops. These empires declined amid environmental stresses and internal conflicts. In the Late Intermediate Period (c. 1000-1438 CE), the Chimú kingdom dominated the northern coast with its capital , the largest adobe city in pre-Columbian at 20 square kilometers, housing up to 30,000 people. Chimú engineers built extensive canals and reservoirs, supporting intensive agriculture. Concurrently, the Chachapoya in the northeastern Andes constructed cliffside mausoleums and circular structures; a 2025 survey at Gran Pajatén revealed over 100 previously unknown buildings, more than doubling known features and highlighting their architectural complexity in remote montane settings. The (Tawantinsuyu) unified the Andes from 1438 to 1533 CE under and successors, expanding from to control territories spanning modern , , , , and . Central to Inca achievements was the Qhapaq Ñan road system, totaling approximately 40,000 kilometers of engineered paths with suspension bridges and way stations (tambos) for administrative and military efficiency. Terrace farming scaled massively, with aqueduct-fed fields producing surplus for storage in qollqas, while produced alloys for elite goods. The labor system conscripted subjects for rotational , building at the cost of personal autonomy and occasional overexertion, as communities provided able-bodied adults for state projects without direct compensation beyond sustenance.

Colonial Era and European Contact

The Spanish conquest of the began with Pizarro's expedition, culminating in the capture of Inca emperor on November 16, 1532, at , where Pizarro's force of fewer than 200 men ambushed thousands of unarmed Inca attendants during a staged meeting, leveraging superior weaponry and surprise. This event exploited Inca internal divisions from a recent , enabling Pizarro to secure a massive ransom in gold and silver before executing Atahualpa in 1533, which facilitated the rapid occupation of by 1534 and the collapse of centralized Inca resistance. The conquest's primary drivers were economic, as Spanish forces sought precious metals to fund imperial ambitions, transforming the Andes into a resource extraction zone under the established in 1542. The discovery of vast silver deposits at in 1545 ignited a mining boom, with the mountain fueling Spain's economy through forced indigenous labor under the system, an adaptation of Inca rotational service. 's output accounted for approximately 40% of global silver production from the 16th to 18th centuries, processed via mercury amalgamation after 1572, which exported wealth to but devastated local populations through exhaustion and toxicity. This extractive focus prioritized flows over , with Spanish crown revenues peaking in the late before declining due to vein exhaustion and . Indigenous Andean populations, estimated at around 10 million under Inca rule, plummeted to about 1 million by the early , chiefly from introduced diseases like —against which natives lacked immunity—exacerbated by warfare, , and relocation. The system, granting conquistadors rights to indigenous and labor in exchange for nominal instruction, institutionalized exploitation, compelling communities to deliver goods and services while fostering demographic shifts through Spanish-indigenous unions that birthed populations. Despite the collapse, Spanish administrators retained Inca like roads and terraces for administrative and economic efficiency, blending coercive labor with pre-existing networks to sustain colonial control until the late .

Independence and 20th-21st Century Developments

The wars of independence in the Andean region, spanning roughly 1810 to 1826, dismantled Spanish colonial rule through campaigns led by in the north and in the south. Bolívar's forces liberated present-day , , , and , culminating in decisive victories such as the Battle of Junín on August 6, 1824, which weakened royalist control in . San Martín's crossed the in 1817, securing Chilean independence at the on February 12, 1817, and later aiding Peru's liberation after his 1822 meeting with Bolívar at . These efforts established independent republics but left fragmented borders inherited from imprecise colonial lines, sowing seeds for future conflicts. Post-independence border disputes persisted, often escalating into wars over resource-rich territories. The (1879–1884) saw Chile seize nitrate provinces from and , resolving maritime access claims in Chile's favor through the 1904 and 1929 treaties, though Bolivia's landlocked status remains a grievance. Ecuador and clashed repeatedly over Amazonian lands, with the 1941 war and 1995 Cenepa conflict settled by the 1998 Brasilia Peace Agreement, ceding Ecuador a nominal river outlet. The (1932–1935) between and , while partially extramountainous, drained Bolivian resources amid Andean highland instability. These resolutions, frequently mediated internationally, stabilized frontiers but underscored how geographic isolation and mineral incentives fueled . Twentieth-century Andean politics were marked by recurrent military coups and dictatorships, reflecting elite power struggles and economic volatility tied to export commodities. Bolivia endured over 190 coups since independence, including Hugo Banzer's 1971–1978 regime, which suppressed dissent while promoting tin exports. In Chile, Augusto Pinochet's 1973 coup ousted Salvador Allende amid hyperinflation exceeding 500% annually; his 1973–1990 rule implemented neoliberal reforms advised by the "Chicago Boys," privatizing state firms, liberalizing trade, and slashing tariffs from 94% to 10%, which spurred GDP growth averaging 7% yearly from 1984–1990 after initial recessions. These policies, including pension privatization and labor market deregulation, laid foundations for sustained expansion, with poverty falling from 45% in 1982 to 15% by 1990, though at the cost of documented human rights violations. Peru under Alberto Fujimori (1990–2000) similarly stabilized hyperinflation via austerity, fostering mining-led recovery. Into the , Andean economies leveraged commodity supercycles, particularly from 2003–2013, driven by Chinese demand for and metals, boosting export revenues; Chile's output alone generated $20 billion annually by 2010, comprising 50% of government income. Peru's sector expanded amid the boom, with production rising 150% from 2000–2020, fueling GDP growth to 6.5% yearly pre-2014. This resource dependence amplified modernization but exposed vulnerabilities to price swings, as seen in post-2014 slowdowns. Recent developments center on the —spanning , , and 's Andean salt flats—where reserves exceed 50% of global totals, prompting exploration surges in the amid electric vehicle battery demand projected to quadruple lithium needs by 2030. advanced projects like Cauchari-Olaroz, reaching 40,000 tons/year by 2023 via public-private partnerships. nationalized efforts under state firm YLB, signing deals for 21 plants by 2025 despite extraction delays from high-altitude . reformed its 40-year in 2023, auctioning brine blocks and approving 10+ projects, aiming for 300,000 tons by 2030 to capture EV value. These initiatives, projected to add $10–20 billion in annual exports regionally, underscore causal links between mineral endowments and developmental trajectories, though extraction challenges like use in arid zones persist.

Modern Economy and Infrastructure

Urban Centers and Population Distribution

The Andean region supports approximately 85 million inhabitants across , , , , , , and , with demographic concentrations favoring habitable intermontane valleys and high plateaus over steep cordilleras. Population density reaches up to 460 persons per square kilometer in arable highland valleys of countries like , where flatter terrains enable settlement and farming. These patterns reflect geographic constraints, as rugged topography limits widespread habitation, channeling growth into basins such as the around , , and volcanic inter-Andean valleys near , . Major urban centers dominate this distribution, including (7.7 million residents) in Colombia's Andean highlands, population exceeding 2.7 million) in Ecuador's equatorial basin, (metro 1.9 million) as the world's highest national capital at 3,640 meters elevation, and Santiago (6.9 million) in Chile's central valley adjacent to the . Other notable cities like (3.9 million) and (0.43 million) further illustrate clustering in fertile valleys conducive to historical and modern development. Post-1950s rural-urban migration accelerated , driven by economic opportunities and agricultural , transforming Andean societies from predominantly rural to over 75% urban in nations like by the late 20th century. This shift concentrated populations in valley cities, exacerbating infrastructure demands while reducing rural highland densities. In and , such movements from 1940 onward swelled primate cities like and , though the latter lies coastal, with Andean inflows sustaining highland metros. High-altitude residents, particularly indigenous Quechua and Aymara groups, demonstrate evolved physiological adaptations to hypoxia, featuring elevated levels that boost blood oxygen transport compared to lowlanders—averaging 20% higher concentrations without the excessive erythrocytosis seen in unadapted individuals. Genetic studies identify variants in genes like EGLN1 and EPAS1 influencing this response, enabling sustained performance at elevations above 3,000 meters, though affects 5-10% of long-term dwellers. These traits, distinct from Tibetan hyperventilation strategies, underscore Andean-specific evolutionary paths to altitude tolerance.

Agriculture and Irrigation Systems


Pre-Columbian Andean societies, including the Inca, developed terracing to cultivate steep slopes, enabling the production of staple crops like potatoes and at elevations up to 4,000 meters. These stone-walled platforms retained , reduced , and optimized microclimates for diverse varieties, with potatoes domesticated over 7,000 years ago yielding thousands of resilient types adapted to harsh conditions.
Inca engineers constructed aqueducts and canals to divert and rainfall, sustaining in arid highlands through gravity-fed systems that included subterranean channels minimizing evaporation. These networks, spanning thousands of kilometers, supported practices alternating potatoes, beans, and grains to maintain and control pests.
Contemporary high-altitude farming in the Andes continues this legacy, producing yields of up to 2 tons per in and despite frost and thin soils, while potato cultivation feeds millions in subsistence economies. Ancient techniques underpin productivity, as terraces and raised fields around enhance drainage and warmth for tubers and cereals.
In Andean coastal valleys, modern expands ; Peru's Chavimochic project, operational since 1984, diverts Santa River water to irrigate 78,000 hectares, achieving yields exceeding 20 tons per hectare and enabling avocado production for . Phase III, underway as of 2024, adds 63,000 hectares via drip systems, the world's largest such initiative.
Peru's Andean-influenced regions drive exports, with 630,000 metric tons of avocados shipped in 2025 and volumes reaching 39,000 tons by mid-year, reflecting irrigation-enabled efficiencies; Ecuador's foothill farms similarly contribute over 300,000 tons of avocados annually.

Mining and Resource Extraction

The Andean range hosts extensive mining operations extracting , , silver, and , with and leading in copper output through large-scale open-pit methods that enable efficient bulk extraction from porphyry deposits. In 2023, accounted for approximately 24% of global copper production, totaling around 5.4 million metric tons from major sites like and , where advancements in autonomous haul trucks and ore processing have boosted yields despite declining ore grades. Lithium extraction in the —spanning , , and —relies on evaporative concentration of from high-altitude salars, with emerging direct lithium extraction (DLE) technologies promising faster recovery rates and lower use compared to traditional pond methods. The region holds over half of global reserves, estimated at more than 40 million metric tons, supporting scaled production for batteries amid rising demand. Between 2023 and 2025, investments in the Triangle, including Chinese-backed projects in aiming for 100,000 tons annual output by 2028, have advanced processing facilities to supply materials, reducing reliance on imported energy resources. Mining contributes significantly to national economies, with the sector comprising about 13.6% of Chile's GDP in 2022 and generating over 300,000 direct jobs, many in remote northern regions where operations provide stable employment and development. These activities drive technological innovations, such as AI-optimized drilling and for operations, enhancing productivity in arid Andean environments.

Transportation Networks

The rugged terrain of the Andes, characterized by elevations often surpassing 4,000 meters, seismic instability, and proneness to landslides and heavy snowfall, imposes formidable engineering challenges on transportation infrastructure, requiring reinforced structures, avalanche barriers, and altitude-adapted designs to ensure viability. Highways constitute the dominant mode of overland connectivity, with key trans-Andean routes like segments of the Pan-American Highway navigating steep gradients and high passes such as Paso Los Libertadores at 3,220 meters elevation, which links Chile and Argentina but faces frequent winter closures due to ice accumulation. To address pass-related disruptions, infrastructure includes shorter tunnels and viaducts, though ambitious proposals for longer bores—such as a planned 13-kilometer tunnel at over 4,000 meters to connect Argentina and Chile—aim to enable year-round access by avoiding snow-bound summits. Rail networks, historically engineered with rack systems to conquer Andean slopes, experienced sharp decline after the 1950s amid rising road competition and maintenance costs, culminating in widespread abandonments. The , which linked , to Los Andes, , via a 3,000-meter summit tunnel completed in 1910, operated freight until the early 1980s when El Niño floods caused irreparable track washouts, leading to service cessation on much of the line. Similar fates befell Peruvian and Bolivian lines, where post-1950s shifts to truck transport and deferred repairs eroded viability, leaving only isolated segments for mining haulage. Aviation fills critical gaps in remote Andean zones, with high-altitude airports employing longer runways and specialized procedures to counter thin air's impact on lift; facilities like those serving , , at 4,061 meters, handle substantial domestic and regional traffic despite operational constraints from weather and hypoxia risks. Recent initiatives target enhanced cross-continental links, notably the Brazil-Peru Bioceanic Railway, a proposed 4,000-plus kilometer line traversing Andean peripheries to connect Atlantic ports like Santos to Pacific terminals via , with and signing a July 2025 planning accord to feasibly assess routes amid terrain hurdles. has affirmed no immediate funding commitment, emphasizing studies on environmental and logistical feasibility before advancing construction. These corridors underscore ongoing reliance on hybrid road-rail solutions to surmount the Andes' isolation, prioritizing seismic-resilient alignments over expansive tunneling where gradients permit.

Resource and Development Debates

Environmental Claims versus Economic Realities

Andean glaciers experienced significant advances during the (roughly 1300–1850 CE), reaching maxima around 1600–1700 CE before initiating retreats that predated modern industrial activity. Recent studies indicate accelerated area loss since the late , with tropical Andean s retreating at rates unprecedented within variability over the past three decades, primarily linked to rising temperatures. Environmental advocacy often amplifies these trends to attribute losses directly to local extraction activities, yet empirical data reveal that fluctuations have long responded to climatic forcings, with operations contributing negligibly to melt through indirect demands in headwater basins. Mining's water consumption in Andean countries remains a fraction of total basin inflows, typically under 5% nationally in despite higher localized draws in concession areas. In Chile's arid north, where and dominate, sector use accounts for about 20% of industrial withdrawals but less than 4% of overall national freshwater, with most operations over 80% of process to minimize basin strain. Claims of systemic depletion overlook these efficiencies and the dominance of agricultural (up to 70% of basin use) and evaporative losses in driving , while extraction revenues have enabled plants and upgrades that bolster regional . Deforestation in the Andean proceeds at modest rates, averaging below 0.5% annually in non-Amazonian zones like Colombia's Andean municipalities, far lower than the broader Amazon basin's 1–2% losses. Productive reforestation efforts counteract much of this, with initiatives planting millions of native trees across , , and —such as Acción Andina's 2.1 million seedlings by 2023—enhancing soil stability and watershed protection in degraded mining-adjacent lands. Resource extraction has underpinned alleviation through fiscal transfers funding , with 's sector—expanded via 1980s privatizations—driving average annual GDP growth of 7% from 1985–1997 and reducing from 38% in 1990 to under 5% by 2020. royalties and exports, comprising 10–15% of GDP in and , have financed roads, , and in remote Andean districts, yielding causal gains in human development indices that outweigh localized ecological costs when measured against baseline stagnation. These outcomes challenge narratives prioritizing static preservation over adaptive development, as revenue streams enable resilience against climatic pressures like variable precipitation.

Indigenous Rights and Extraction Conflicts

Indigenous communities in the Andean —spanning , , and —have raised concerns over projects, particularly extraction, alleging inadequate (FPIC) and threats to traditional livelihoods. These disputes often center on land access and resource use, with groups like the Kolla in 's Jujuy province protesting 2023 constitutional reforms that eased restrictions on extractive activities in sensitive areas. National governments counter that subsurface minerals belong to the state, prioritizing economic sovereignty and development needs amid global demand for battery materials. Extraction contracts have delivered tangible benefits, including provincial royalties and job creation; Argentina's lithium sector, for instance, bolstered mining exports to 2,321 million dollars in the first seven months of 2023 alone. In Jujuy, state-owned enterprises hold stakes in major projects, channeling revenues toward while providing , though critics note limited high-skill opportunities for locals. Such agreements underscore potential mutual gains, contrasting with opposition that risks forgoing prosperity for communities integrated into formal economies. Water depletion claims in salars feature prominently in indigenous critiques, with assertions that brine evaporation for concentrates aquifers vital for herding and agriculture. However, hydrologic data reveal recharge mechanisms, such as surface rainfall in , sustaining basin levels despite extractions, while direct lithium extraction methods allow reinjection of processed to minimize net losses. Regulated operations thus differ from —prevalent in and —which inflicts unregulated harm via mercury contamination, , and armed incursions, endangering indigenous territories far more acutely. Debates extend to the scope of indigenous influence, with some viewpoints critiquing veto-like powers as impediments to national advancement; , for example, scaled back consultation laws in to prevent localized blocks on broader economic projects. Similarly, Ecuadorian analyses highlight how constitutional veto provisions have fueled contestation, delaying while alternative consultation frameworks could align rights with development. Prioritizing property rights and contractual benefits over absolute vetoes facilitates equitable resource stewardship, enabling indigenous participation without stalling regional growth.

Notable Peaks

Highest Peaks by Region

The northern Andes, spanning and , feature relatively lower summits compared to southern sectors, with elevations generally below 6,000 meters due to the range's tectonic and erosional history. In , stands as the highest at 4,978 meters in the Sierra Nevada de Mérida, notable for its accessibility via cable car and historical significance in early 20th-century surveys that confirmed its prominence amid glacial retreat. In , reaches approximately 5,775 meters in the , an isolated massif bordering the , where empirical GPS measurements in recent decades have refined elevations amid disputes over exact heights with neighboring at around 5,720 meters; these peaks demarcate coastal and Andean boundaries, with climbing records dating to the 1930s highlighting technical challenges from loose rock. Further south in and , the equatorial Andes host higher volcanic and glaciated peaks, reflecting subduction-driven uplift. 's , at 6,263 meters, is the range's easternmost ultra-prominent summit, its height verified by 19th-century expeditions and modern , though its equatorial bulge makes it the farthest point from Earth's center rather than sea-level tallest. 's Sur, the highest non-volcanic peak at 6,768 meters in the , was precisely measured post-1970 avalanche events that reshaped its north face, underscoring seismic vulnerabilities in the region. In the central Andes of and southern extensions into and , elevations peak due to arid plateau conditions preserving massifs. 's , at 6,542 meters in the Cordillera Occidental, represents the Altiplano's volcanic heritage, with surveys confirming its isolation and role in border . The southern Andes culminate in 's at 6,960.8 meters, the hemisphere's highest, officially measured by Argentine geodetic institutes in the 2000s using to resolve prior discrepancies, situated in near ; its Polish Glacier route saw first ascents in 1897, emphasizing non-technical but high-altitude risks. Nearby, -'s at 6,893 meters, the world's highest volcano, borders the Atacama and , with elevations corroborated by 1950s expeditions amid dry, extreme conditions.
RegionHighest PeakElevation (m)Country(ies)Notes
Northern (Venezuela/Colombia)5,775Isolated coastal massif; GPS-refined height.
Equatorial (Ecuador/Peru)Huascarán Sur6,768Cordillera Blanca; post-avalanche surveys.
Central/Southern (Bolivia/Chile/Argentina)6,960.8Geodetic official measurement; climbing pioneer.

References

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