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
Ojos del Salado of the Nazca Plate beneath the South America Plate became increasingly shallower and this caused volcanism to shift from the Maricunga Belt to the Ojos del Salado region. The Paleozoic basement crops out only northwest of Nevado Tres Cruces. Other geologic units in the region are Oligocene sedimentary units and volcanic rocks ranging from Oligocene age to less than 1.5 million years old. The area is part of a tectonic boundary between a volcanically active region north of the boundary and a less volcanically active region south of the boundary, which is also characterized by geographical differences, e.g. the presence