Nevado Sajama is an extinct stratovolcano and the highest peak in Bolivia. The mountain is located in the Oruro Department, Sajama Province, Curahuara de Carangas Municipality, Sajama Canton. It is situated in the Sajama National Park in the southwest area of the country some 16–24 km (10-15 mi) from the border with Chile. The peak is an isolated cone, but is geologically complex, with lava domes of andesitic and rhyodactic composition overlain by an andesitic stratovolcano. The date of the most recent eruption is uncertain, although Holocene activity is assigned to the volcano by many. The treeline of Polylepis tarapacana on the volcano is as high as 5,200 m above sea level, one of the highest altitudes trees can be found growing anywhere in the world.