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 Zone of the Andes. It is composed from andesite with the exception of basaltic cones and lava flows on the eastern side. These cones are part of the Peinado lineament and a sample was dated 200,000 years ago by argon chronology. 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.
