A geologically young system, the Andes were originally uplifted in the Cretaceous and Tertiary periods. They are still rising; volcanoes and earthquakes are common. The folded ranges are discontinuous—merging and bifurcating within the system—but as a whole they form one of the world's most important mountain masses. They are loftier than any other mountains except the Himalayas, with many snowcapped peaks more than 22,000 ft (6,700 m) high. Andean waters reach the Orinoco, the Amazon, and the Río de la Plata.
Far south in Tierra del Fuego, the mountains run east and west, then turn north between Argentina and Chile. The westernmost of the mountains run into the sea, lining the coast of S Chile with islands. In the Patagonian Andes are high, glacier-fed lakes in both Argentina and Chile.
The highest range of the Andes is on the central and northern Argentine-Chilean border; Aconcagua (22,835 ft/6,960 m; highest mountain of the Western Hemisphere) and Tupuncato are there. Between the peaks is Uspallata Pass, the route of the former Transandine Railway, with the Christ of the Andes. Other major peaks such as Llullaillaco flank the main range, and in N Chile sub-Andean ranges enclose the high, cold Atacama Desert.
The central Andes broaden out in Bolivia and Peru in multiple ranges (c.400 mi/640 km wide) with high plateau country (the altiplano) and many high intermontane valleys, where the great civilization of the Inca had its home. High in the mountains on the Peru-Bolivia border is Lake Titicaca. In Bolivia are the notable volcanoes, Illimani and Illampú, and in S Peru is El Misti. The western or coastal range in Peru has lofty peaks (notably Huascarán) and is crossed by the highest railroad of the Andes (from La Oroya to Lima).
The ranges approach each other again in Ecuador, where the N Andes begin. Between two volcanic cordilleras (including the cloud-capped Chimborazo and Cotopaxi) are rich intermontane basins. In Colombia the Andes divide again, the western range running between the coast and the Cauca River, the central between the Cauca and the Magdalena rivers, and the eastern running north parallel to the Magdalena River, then stretching out on the coast into Venezuela. The Andes continue in some of the islands of the West Indies, and in Panama N Andean spurs connect with the mountains of Central America and thus with the Sierra Madre and the Rocky Mts.
The plateaus and valleys of Bolivia, Peru, Ecuador, and Colombia have been peopled since remote times and saw the rise of not only the Inca and the Chibcha but some of the earliest native civilizations in the Western Hemisphere. Today the Quechua and Aymara tribes are the main indigenous inhabitants of the Andes. Agriculture was the basis of these cultures (the native llama and alpaca were domesticated later), and the lands there are still tilled mainly for subsistence crops. Because of a scarcity of water, however, agriculture is difficult. Tobacco, cotton, and coffee are grown and exported. Copper, silver, tin, iron, and gold are mined, and petroleum has been found. Pack trails are the most efficient means of communication in the Andes. Although there is some rail passage through the mountains, the inhabitants of the Andes do not depend on trains for the maintenance of their economy. Certain Andean areas have developed a tourist trade.
See A. G. Ogilvie, Geography of the Central Andes (1922); C. Arthaud and F. Hébert-Stevens, The Andes: Roof of America (tr. 1956); P. E. James, Latin America (1969, repr. 1988); T. Kazami, The Andes (1972); W. S. Pitcher, Magmatism at a Plate Edge: The Peruvian Andes (1985); D. Murphy, Eight Feet in the Andes (1986); S. Lamb, Devil in the Mountain: A Search for the Origin of the Andes (2004).
The Andes form the world's longest exposed mountain range. They lie as a continuous chain of highland along the western coast of South America. The range is over 7,000 km (4,400 miles) long, 200-700 km (300 miles) wide (widest between 18° to 20°S latitude), and of an average height of about 4,000 m (13,000 ft).
The Andean range is composed principally of two great ranges, the Cordillera Oriental and the Cordillera Occidental, often separated by a deep intermediate depression, in which arise other chains of minor importance, the chief of which is Chile's Cordillera de la Costa. Other small chains arise on the sides of the great chains. The Cordillera de la Costa starts from the southern extremity of the continent and runs in a northerly direction, parallel with the coast, being broken up at its beginning into a number of islands and afterwards forming the western boundary of the great central valley of Chile. To the north this coastal chain continues in small ridges or isolated hills along the Pacific Ocean as far as Venezuela, always leaving the same valley more or less visible to the west of the Western Great Chain. The mountains extend over seven countries: Argentina, Bolivia, Chile, Colombia, Ecuador, Peru and Venezuela, 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.
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".
The Andes fundamentally are the result of plate tectonics processes, caused by the subduction of the Nazca plate beneath the South American plate. The boundary between the two plates is marked by the Peru-Chile oceanic trench.
The formation of the Andes began in the Jurassic Period. It was during the Cretaceous Period that the Andes began to take their present form, by the uplifting, faulting and folding of sedimentary and metamorphic rocks of the ancient cratons to the east. Tectonic forces along the subduction zone along the entire west coast of South America where the Nazca Plate and a part of the Antarctic Plate are sliding beneath the South American Plate continue to produce an ongoing orogenic event resulting in minor to major earthquakes and volcanic eruptions to this day. In the extreme south a major transform fault separates Tierra del Fuego from the small Scotia Plate. Across the wide Drake Passage lie the mountains of the Antarctic Peninsula south of the Scotia Plate which appear to be a continuation of the Andes chain.
The Andes range has many active volcanoes, including Cotopaxi, one of the highest active volcanoes in the world.
The Andes is rich in fauna and flora. About 30,000 species of vascular plants live in the Andes with roughly half being endemic to the region, surpassing the diversity of any other hotspot. With almost 1000 species, of which roughly 2/3 are endemic to the region, the Andes is the most important region in the world for amphibians. For other major groups the numbers are equally impressive: Almost 600 species of mammals (13% endemic), more than 1,700 species of birds (c. 1/3 endemic), more than 600 species of reptiles (c. 45% endemic), and almost 400 species of fishes (c. 1/3 endemic).
Rainforests used to encircle much of the northern Andes but are now greatly diminished, especially in the Chocó and inter-Andean valleys of Colombia. The small tree Cinchona pubescens, a source of quinine which is used to treat malaria, is found widely in the Andes as far south as Bolivia. Other important crops that originated from the Andes are tobacco and potatoes. The high-altitude Polylepis forests and woodlands are found in the Andean areas of Colombia, Ecuador, Peru, Bolivia and Chile. These trees, by locals referred to as Queñua, Yagual and other names, can be found at altitudes of above sea level. It remains unclear if the patchy distribution of these forests and woodlands is natural, or the result of clearance which started 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. A number of species such as the Royal Cinclodes and White-browed Tit-spinetail are associated with Polylepis, and consequently also threatened.
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 a large part 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. The massive Lake Titicaca hosts several endemics, among them the highly endangered Titicaca Flightless Grebe and Titicaca Water Frog. A few species of hummingbirds, notably some hillstars, can be seen at altitudes above , but far higher diversities can be found at lower altitudes, especially in the humid Andean forests ("cloud forests") growing on slopes in Colombia, Ecuador, Peru, Bolivia and far north-western Argentina. These forest-types, which includes the Yungas and parts of the Chocó, are very rich in flora and fauna, although few large mammals exists, exceptions being the threatened Mountain Tapir, Spectacled Bear and Yellow-tailed Woolly Monkey. Birds of humid Andean forests include Mountain-Toucans, Quetzals and the Andean Cock-of-the-rock, while mixed species flocks dominated by tanagers and Furnariids commonly are seen - in contrast to several vocal, but typically cryptic, species of wrens, tapaculos and antpittas. As a direct opposite of the humid Andean slopes are the relatively dry Andean slopes in most of western Peru, Chile and Argentina. Along with several Interandean Valles, they are typically dominated by deciduous woodland, shrub and/or xeric vegetation, reaching the extreme in the slopes near the virtually lifeless Atacama Desert.
The Inca Empire developed in the northern Andes during the 1400s. The Incas formed this civilization through imperialistic militarism as well as careful and meticulous governmental management. The government sponsored the construction of aqueducts and roads, some of which, like those created by the Romans a thousand years before them, are still in existence today. The aqueducts turned the previously scattered Incan tribe into the agricultural and eventually militaristic masters of the region.
Devastated by deadly European diseases to which they had no immunity, and by a terrible civil war, in 1532 the Incas were defeated by an alliance composed by tens of thousands allies from nations they had subjugated (Huancas, Chachapoyas, Cañaris, etc) and a small army of 180 Spaniards led by Pizarro. One of the few Inca cities the Spanish never found in their conquest was Machu Picchu, which lay hidden on a peak on the edge of the Andes where they descend to the Amazon. The main surviving languages of the Andean peoples are those of the Quechua and Aymara language families.