Introduction to The Andes
The Andes Mountains, in South America, are the world's longest chain of mountains above sea level.Andes, (Spanish: Cordillera de los Andes ), the great mountain system of South America. It extends near the continent's Pacific coast for more than 4,000 miles (6,400 km), running through Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina. After the towering Himalayan system of Asia, the Andes are the highest mountains in the world.
Along much of its length, the system divides into two, sometimes three, roughly parallel chains. These are the Cordillera Occidental, the western chain; the Cordillera Central; and the Cordillera Oriental, the eastern chain. Various local names are used to designate parts of these chains.
Geographical Divisions
The Andes are a geologically young and complex series of folded and faulted mountains. There are major volcanic areas, especially in southern Colombia and Ecuador, from southern Peru to northern Argentina, and in the south-central part of Chile. The entire Andean region is an active earthquake zone.
The Northern Andes begin in Venezuela and Colombia, where the mountain ranges rise almost directly from the Caribbean sea. In Colombia, deep river valleys divide the Andes into the three distinct cordilleras. Farther south, in Ecuador, the mountains consist of two chains, separated by a deep rift valley. Dotting the chains are numerous volcanoes, including Chimborazo and Cotopaxi. The Andes reach their narrowest point in Ecuador, where the crests of the ranges are as little as 20 miles (32 km) apart.
The Central Andes begin in northern Peru and broaden into high plateaus, on which are mountain ranges and volcanic peaks. As in the northern section, there are two or three major ranges depending on location.
In southern Peru and western Bolivia, the ranges enclose an area of high intermontane basins called the Altiplano (high plain). Most of this area lies at elevations of more than 12,000 feet (3,600 m). To the southeast, along the eastern margin of the Andes, is a high, dry region called the Puna. The Andes are at their widest in Bolivia, where the eastern and western ranges are as much as 400 miles (640 km) apart.
As the Andes narrow in northern Argentina and Chile, they form a single principal range. Here are the highest mountains of the Americas, including many volcanoes.
The Southern Andes stretch from central Chile to the tip of the continent at Cape Horn. In general, they are lower than the ranges to the north, although there are high, isolated volcanic peaks. The mountains have been heavily glaciated, especially in the extreme south, where large glaciers still exist. For much of their course the Southern Andes plunge directly into the sea, creating a rugged, indented shoreline, with many offshore islands.
Rivers and Lakes
Except in Venezuela, where all rivers flow to the Atlantic Ocean, the Andes form the divide between Atlantic and Pacific drainage. Hundreds of large rivers flow eastward to the Atlantic. Most are either headstreams or tributaries of the great Orinoco, Amazon, and Paraná systems. No large rivers flow westward to the Pacific.
There are few lakes, other than glacial ones in southern Chile. Lake Titicaca, on the Altiplano between Peru and Bolivia, is South America's largest freshwater lake. It is also the highest navigable lake in the world. The only other large lake is Lake Poopó, also on the Altiplano.
Passes and Transportation
Passes through the Andes are high and difficult to approach, but several are used by railways, roads, or both. Uspallata Pass on the Chile-Argentina border is followed by the Pan American Highway. Railroads have been built at great heights in the Andes to bring out valuable minerals, especially in Peru, Bolivia, and Chile. Most traffic in the mountains, however, is carried on unpaved roads and trails, mainly by burros and llamas. Principal cities are linked by airlines.
Climate and Vegetation
Since the Andes stretch from about 10º North latitude to 55º South, there is a wide climatic range. In the low equatorial foothills, temperatures average about 80º F. (27º C.) the year long. In contrast, the cold, wet, almost uninhabitable areas of the extreme south have average temperatures a little over 40º F. (4º C.). The effects of increasing elevation, and consequent lower temperatures, are felt everywhere. The highest mountains are mantled with snow throughout the year even near the Equator.
In the tropical areas, climate and vegetation depend chiefly on elevation. The foothills, up to about 3,000 feet (900 m) above sea level, are called the tierra caliente (hot land), an area of tropical rain forests. Above this zone, extending to about 6,500 feet (2,000 m), is the tierra templada (temperate land), with mixed deciduous trees and grasslands. Still higher, up to about 10,000 feet (3,000 m), is the tierra fría (cold land), with coniferous forests, hardy grasses, and shrubs. Still higher, there are Alpine pastures, called páramos, that extend above the tierra fría to the snow line.
Agriculture
Because of rough terrain and high elevations, very little of the Andes is suitable for agriculture. Most of the people live by subsistence farming. However, there are small areas of the tierra caliente where tropical cash crops are raised. The most valuable are bananas, sugar, and cotton. Coffee is the chief commercial crop on the tierra templada, especially in Colombia.
Subsistence farming extends through the middle and highland zones. On the tierra templada, corn and temperate fruits and vegetables are grown; on the tierra fría, hardy strains of wheat and barley. At high elevations Indians raise llamas and alpacas. These animals, unique to the Andes, produce wool and milk and are agile pack animals. Llamas are also used for meat.
Mining
Some of the world's richest copper mines are in the high mountains of Peru and Chile. Bolivia has long been one of the world's leading tin producers. Peru and Bolivia, as in the days of Spanish rule, are major producers of silver. Platinum, tungsten, vanadium, molybdenum, bismuth, lead, zinc, and gold are also mined in the Andes. Colombia is famous for its gem emeralds.
The People
Indians are the native peoples of the Andes. The chief group is the Quechua, the dominant people of the great Inca empire. Their language, also called Quechua, is widely spoken by Indians in Peru, Bolivia, Ecuador, Chile, and Argentina. Other groups are Chibcha of Columbia and the Aymará of Bolivia and Peru. People of Spanish descent and mestizos (people of mixed Spanish-Indian culture) live mainly in the cities.