Llullaillaco

Llullaillaco (ʎuʎajˈʎako) is a dormant stratovolcano at the border of Argentina (Salta Province) and Chile (Antofagasta Region). 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. It is the second highest active volcano in the world after Ojos del Salado. Llullaillaco formed during two different phases in the Pleistocene-Holocene out of dacitic lava flows. The oldest rocks are about 1.5 million years old. About 150,000 years ago, the volcano's southeastern flank collapsed, generating a debris avalanche that reached as far as from the summit. The youngest dated rocks were erupted 5,600 ± 250 years ago in the summit region, but there are reports of activity from the 19th century. The mountain's first recorded climb was in 1950, but traces of earlier climbs and a number of archaeological sites were found on the mountain and at its feet; Llullaillaco marks the highest archaeological site in the world. In 1999, the mummified remains of three children, known as the Children of Llullaillaco, were found at its summit. They are presumed to have been human sacrifices. Mice have been observed in the summit region, they are the highest finding of a mammal in the world. The name Llullaillaco is derived from the Quechua word llulla meaning "false", "lie" or "deceitful" and yaku or llaco meaning "water". This name probably refers to the meltwater from snow, which flows down the slopes but then is absorbed into the soil; normally mountains are sources for water. It is possible that it instead refers to the precipitation regime, which starting from Llullaillaco becomes dominated by winter precipitation. Another translation in Aymara is "hot water". Volcanism in the Andes is caused by the subduction of the Nazca Plate and the Antarctic Plate beneath the South America Plate. The Nazca Plate subducts at a speed of and the Antarctic Plate at a speed of .