II.

The Principal Ranges of the Andes

The mountain belt is generally about 300 km (about 200 mi) wide, except in Bolivia, where it expands to twice that width. From north to south the belt can be divided into three regions: a northern section in Venezuela, Colombia, and northern Ecuador; a central section in southern Ecuador, Peru, Bolivia, and the northern regions of Argentina and Chile; and a southern section in the southern regions of Argentina and Chile.

The northern Andes curve in an arc from northeast to southwest. The arc consists of three main parallel ranges, known as the Cordillera Occidental (Western Cordillera), the Cordillera Central (Central Cordillera), and the Cordillera Oriental (Eastern Cordillera). The term cordillera, which is now used to describe mountain ranges in many parts of the world, comes from a Spanish word meaning rope. Early European explorers used the word to describe the roughly parallel formation of many Andean ranges. In the north the ranges fan out. The Cordillera Oriental divides into the Cordillera Mérida, which extends along the east coast of Lake Maracaibo in Venezuela, and the Sierra de Perijá, which extends to the west of Lake Maracaibo along the borders of Colombia and Venezuela. Both of these ranges extend to the Caribbean Sea. Farther south the three major ranges draw closer to one another in Colombia and narrow further in Ecuador to form two main ranges.

The central Andes extend from northern Peru southeastward to southern Bolivia and then trend due south. They include the widest part of the mountain system and some of its highest peaks. The two main ranges of the central Andes, which are also known as the Cordillera Occidental and the Cordillera Oriental, enclose the Altiplano, an extensive plateau in Bolivia and southern Peru between 3,600 to 4,000 m (12,000 to 14,000 ft) above sea level. Farther south is another high plateau, called the Puna de Atacama, located mostly in Argentina along the northwest border with Chile and Bolivia.

The southern Andes narrow to form a single range, which curves to the east at its southern end. The highest mountain in the western hemisphere, Aconcagua (6,960 m/ 22,834 ft), is located in this section of the Andes in Argentina. South of Aconcagua the mountains diminish gradually in height. Cerro Yogan, the highest peak on Tierra del Fuego, rises to only 2,469 m (8,100 ft).