The Andes
The Andes are the longest mountain range on Earth, running for 7,000 km down the western side of South America from Venezuela to the southern tip of Chile. They are not as tall as the Himalayas, but they have far more length, dozens of active volcanoes, and the highest mountain outside Asia (Aconcagua). The Andes were also the home of the great Inca civilisation, the largest empire in the Americas before Columbus.
- Length7,000 kmLongest mountain range on Earth
- Countries7From Venezuela to the tip of Chile
- Highest peakAconcagua6,961 m, in Argentina
- Active volcanoesapprox. 150Part of the Ring of Fire
- Famous civilisationThe IncaCapital at Cusco in Peru
- Famous animalLlamas and alpacasDomesticated for thousands of years
The Andes compared to other ranges
The Andes are 45% longer than any other range on Earth. They run nearly a quarter of the way around the world from north to south.
What are the Andes?
The Andes are a continuous chain of mountains following the western coast of South America. They pass through seven countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina. The northernmost part of the Andes (the Cordillera de Mérida in Venezuela) is small. The widest section is in Peru and Bolivia, where the range splits into two parallel chains with the high Altiplano plateau in between. The southern section runs through Patagonia all the way to Cape Horn.
Volcanoes of the Andes
The Andes are home to around 150 active volcanoes, more than any other mountain range. They are part of the Ring of Fire, the horseshoe-shaped chain of volcanoes around the edge of the Pacific Ocean. Famous Andean volcanoes include Cotopaxi in Ecuador (one of the highest volcanoes in the world), Villarrica in Chile, and Llullaillaco on the Chile-Argentine border. The volcanoes erupt regularly; major eruptions have caused tsunamis, mudflows and ash falls across the continent.
The Inca civilisation
The Andes were the home of the Inca empire, the largest civilisation in the Americas before Christopher Columbus. At its peak around 1500 AD, the Inca controlled an empire stretching approx. 4,000 km along the Andes, from southern Colombia to central Chile. The capital was at Cusco in Peru. The Inca built thousands of kilometres of paved roads, suspension bridges, stone cities (including Machu Picchu) and elaborate terraced farms, all without writing, the wheel, or iron tools.
The Inca empire was destroyed in just a few years by the Spanish conquest under Francisco Pizarro starting in 1532. European diseases killed many millions; warfare and slavery killed many more. The descendants of the Inca, the Quechua and Aymara peoples, still live throughout the Andes today.
Wildlife of the Andes
The Andes are home to unique high-altitude wildlife. Llamas and alpacas are domesticated camel relatives kept for wool and pack work; their wild cousins, the guanaco and vicuña, still roam the high grasslands. The Andean condor is the largest flying bird on Earth (by wing area), with a wingspan of over 3 metres. Spectacled bears (the inspiration for Paddington Bear) live in the cloud forests of the northern Andes. Chinchillas and several wild cats also call the high Andes home.
Deeper dive: Andean uplift, the Altiplano and the Atacama
The Andes are the result of the long-running subduction of the Nazca tectonic plate beneath the South American plate. The Nazca plate, which makes up most of the floor of the eastern Pacific Ocean, is being pushed under the western edge of South America at a rate of approx. 7 cm per year. As the Nazca plate descends, it heats up and partially melts; the molten rock then rises to the surface to form the chain of Andean volcanoes. The compression of the South American plate above the subduction zone also folds and lifts the surface rocks to form the non-volcanic peaks. The whole range has been rising for approx. 50 million years and is still rising today.
The Altiplano ("high plain") is a flat-floored basin between two chains of the Andes in southern Peru and Bolivia. It sits at around 3,750 metres above sea level, making it the second-highest plateau on Earth after the Tibetan Plateau. The Altiplano is home to Salar de Uyuni, the largest salt flat on Earth, and to Lake Titicaca. It is also the centre of Andean culture, with most of the rural Quechua and Aymara population living on or around the plateau. The Altiplano formed in part by the same compression that built the Andes; the plateau is essentially Andean crust that has been thickened by tectonic squeezing.
The Atacama Desert of northern Chile, on the western (Pacific) flank of the Andes, is the driest non-polar desert on Earth. The desert exists because of two main factors related to the Andes: the eastern moisture from the Amazon basin cannot cross the mountains because the Andes are too high (the Pacific side is in the "rain shadow" of the Andes), and the cold Humboldt Current along the Chilean coast cools the air over the ocean so it cannot hold much moisture. The combination produces a desert so dry that some parts have never had measurable rainfall in the entire period of European observation.
The highest peak in the range is Aconcagua. For the great range across Asia, see the Himalayas.