Cordillera the cordilleras in Ecuador, Peru, Bolivia, Chile, and Argentina. Mountain ranges of this type have a complex structure, usually the result of folding and faulting accompanied by volcanic activity. In South America the ranges include numerous volcanic peaks. (Though not itself a volcano, Argentina's Mt. Aconcagua, at 22,834 feet (6,960 metres) high, is the highest point in the Western Hemisphere. The Andes cordillera has Ojos del Salado, the highest active volcano in the world, and second highest point in the Western Hemisphere. A number of the volcanoes have been active in historic times. Aside from the volcanic peaks, the crests
Nevado San Francisco They are noteworthy for their olivine phenocrysts. One lava flow less than one million years old reaches a length of . The western slopes contain dacitic lava domes. On the summit lie two circle-shaped constructs, of Inca or Formative period ages. Nevado San Francisco Nevado San Francisco, or Cerro San Francisco (), is a stratovolcano on the border between Argentina and Chile, located just southeast of San Francisco Pass. It is considered extinct and is one of the several peaks in the area, of which the chief is the Ojos del Salado. The volcano is part of the Central Volcanic