The Andes Mountains are part of the Southern Cordillera formed from subduction zone volcanism at the convergent boundary of the Nazca plate and the South American plate. Aracar volcano (summit elev. 6,082 m) is one of many volcanoes in the Andes Range. It is a steep-sided stratovolcano with a youthful-looking summit crater 1-1.5 km in diameter. It is located just east of the Argentina-Chile border. Well-preserved lava flows are found at its base. Prior to a report of ash columns from the summit in 1993, the volcano was not known to be active and very little is known of the volcano's age and history. The large whitish features are very common in the arid Andes; they are called salars. The term salar is used exclusively of the saltwater wetlands of the Puna (high Andes) and can describe not only salt lakes but also temporary marshes, shallow lakes and lagoons, or simply salt crust.