Cerro Bayo

Cerro Bayo is a complex volcano on the northern part border between Argentina and Chile. It consists of four overlapping stratovolcanoes along a north–south line. The main volcano face is located on the Argentine side, thought the summit of the complex is just west of the border, in Chile. The volcano is about 800,000 years old, but it is associated with ongoing ground uplift encompassing also the more northerly Lastarria and Cordón del Azufre volcanoes. The 5,401-metre (17,720 ft) high summit is the source of two viscous dacitic lava flows with prominent levees that traveled to the north.

Elemental sulfur can be found at Bayo, both in the form of high-grade massive deposits and as extinct fumarole chimneys. The volcano formed in three separate phases that produced lava flows. One is dated to 1.6±0.4 million years ago. The volcano can bear snow in winter. The youngest dated rocks are about 23,000 years old; in 2007 a steam eruption were observed by researchers investigating nearby salt pans such as Salar Ignorado.