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
Ojos del Salado of transverse valleys. Ojos del Salado like other major neighbouring mountains is a complex of lava domes and lava flows, with the main summit surrounded by peripheral domes such as El Solo and El Fraile and many other lateral centres. Fumaroles are encountered at the summit of Ojos del Salado within a depression. Potassium-argon dating has yielded ages of 1.2 ± 0.3 million years ago and less than 1 million years ago from rocks north of Ojos del Salado. There are glaciers on the mountain, in the crater and in the form of penitentes which reach heights of . Other