southwestern rim when the climate was wetter. Excess water now leaves through seepage, keeping salt levels low. There are other lakes (usually frozen) at similar altitudes in the Andes. Neighbouring volcanoes Licancabur is just south of Sairecabur, a group of volcanoes which rises to and is an apparent source of recent volcanic activity. East of Licancabur is its companion volcano, Juriques. It is high and has a large——deep crater. West–east alignments of volcanoes like Licancabur and Juriques are common in the region, due to tectonic influences. Araral, Cerro Cabana, Cerro Canapa, Cerros de Tocorpuri, Cerro Linzor, Inacaliri, Inca, Jardin, Putana, Volcan Tatio and Zapaleri are other volcanoes in the neighbourhood of Licancabur. southeast, volcanoes continue with Tocol, the Purico Complex and the -high Llullaillaco. Volcanoes in the Puna de Atacama formed during the Pliocene on Tertiary dacitic, liparitic and rhyolitic ignimbrites. These rocks have a light colour, due to the rhyolite. Licancabur grew over the 1.35-million-year-old Purico, the La Pacana and 1.09±0.56-million-year-old Chaxas ignimbrites. Composition Licancabur has erupted primarily andesite, but basaltic andesite and dacite have also been found. The rocks are dark and grey-coloured. Basaltic andesite is present in the older lavas, and dacite in the more-recent ones. Although the rocks have a seriate texture, the groundmass is hyalopilitic. Phenocrysts include amphibole, clinopyroxene, hornblende, orthopyroxene, plagioclase and titanomagnetite; olivine is found in andesite, and biotite in dacites. Plagioclase is the most common. The amount of phenocrysts in Licancabur's rocks is smaller than that in other Central Volcanic Zone volcanoes, such as Lascar. Clots of crystals with diameters of or larger have also been found. They contain glass, microliths and phenocrysts, and have a composition similar to phenocrysts. The clots probably formed from the aggregation of phenocrysts and their subsequent growth; some phenocrysts in the rocks formed when the clots broke apart. The temperature of Licancabur's pre-eruption magma determined the composition of the rocks; it ranges from for dacite to for andesite. Isotope ratios are typical of Central Volcanic Zone volcanoes. There are differences in the elemental composition of andesites and dacites, with the latter resembling adakites more than the former. Antisana (in the Northern Volcanic Zone) and El Negrillar (in the Central Volcanic Zone) are two other volcanoes which have erupted adakites or adakite-like lavas. Based on its composition, it is assumed that the magma at Licancabur formed from the partial melting of the oceanic crust subducted at the