Ojos del Salado Spanish, comes from the enormous deposits of salt that, in the form of lagoons or “eyes”, appear in its glaciers. An international highway between Chile and Argentina runs north of the mountain. Ojos del Salado along with several other high volcanoes such as El Muerto, El Solo, Nevado Incahuasi and Nevado Tres Cruces lies at the southern end of the Central Volcanic Zone of the Andes. Volcanic activity in the region commenced 26 million years ago in the Cordillera Claudio Gay, at the same time as the neighbouring Maricunga Belt volcanoes were active. Starting 18 million years ago, local subduction
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