Aucanquilcha is a large stratovolcano located in the Antofagasta Region of northern Chile, just west of the border with Bolivia and within the Alto Loa National Reserve. Part of the Central Volcanic Zone of the Andes, it takes the form of a ridge, with a maximum height of 6,176 metres (20,262 ft). The volcano is embedded in a larger cluster of volcanoes known as the Aucanquilcha cluster. This was formed in stages over 11 million years of activity with varying magma output, including lava domes and lava flows. Aucanquilcha was formed from four units that erupted between 1.04 and 0.23 million years ago. During the ice ages, both the principal Aucanquilcha complex and the other volcanoes of the cluster were subject to glaciation, resulting in the formation of moraines and cirques.Photograph credit: Diego Delso