Llullaillaco

Llullaillaco is a dormant stratovolcano on the border between Argentina and Chile. It lies in the Puna de Atacama, a region of tall volcanic peaks on a high plateau close to the Atacama Desert, one of the driest places in the world. Its maximum elevation is most commonly given as 6723 m, making it the second- or third-highest volcano in the world. Despite its height, it is not clear whether the volcano has any glaciers or merely patches of perennial snow and ice. Between 3700 m and 5000 m elevation there is a sparse plant cover, while at lower altitudes the climate is too dry for plants to grow. A species of mouse on Llullaillaco is the highest-living known vertebrate species.

The volcano formed during the Pleistocene in two stages, named Llullaillaco I and Llullaillaco II. The oldest rocks are about 1.5 million years old.