Incahuasi Central Volcanic Zone of the Andes together with about 110 other Quaternary volcanoes, and lies in the southern sector of the volcanic zone; other volcanic zones in the Andes are the Northern Volcanic Zone, the Southern Volcanic Zone and the Austral Volcanic Zone. The history of volcanic activity is poorly known for most of these volcanoes owing to the lack of dating; only a few historical eruptions have been recorded, such as an eruption at Ojos del Salado in 1993. Incahuasi is located northeast of Ojos del Salado, the highest volcano in the world. Both volcanoes are found at the
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