Cerro Bayo Complex, Volcano in Antofagasta de la Sierra Department, Argentina.

Cerro Bayo Complex is a volcanic formation in the Andes that encompasses multiple interconnected volcanic structures across the landscape. The site rises above 5,400 meters and displays visible layers from different volcanic activity periods.

Cerro Bayo is a complex volcano about 800,000 years old, built in three separate phases that produced lava flows; one flow is dated to 1.6±0.4 million years ago. The youngest dated rocks are about 23,000 years old. In 2007 researchers studying nearby salt pans such as Salar Ignorado observed a steam eruption.

The name Cerro Bayo refers to the yellowish colour of the summit area, where elemental sulfur occurs as high-grade massive deposits and as extinct fumarole chimneys. Researchers studying nearby salt pans such as Salar Ignorado observed a steam eruption here in 2007.

The summit lies just west of the Argentine-Chilean border at 5,401 m, reached from the Catamarca side via Antofagasta de la Sierra; the approach crosses high salt-pan terrain such as Salar Ignorado. Snow covers the volcano in winter, and researchers observed a steam eruption there in 2007, so check current activity reports before setting out.

The landscape displays distinct patterns from different lava flows, each leaving its own geological signature on the terrain. These visible differences allow visitors to read the complex's volcanic history directly in the rock formations.