The Laguna Colorada caldera lies east of El Tatio. The terrain at El Tatio is formed by Jurassic-Cretaceous sediments of marine and volcanic origin, Tertiary-Holocene volcanic formations that were emplaced in various episodes, and recent sediments formed by glaciers, alluvium, colluvium and material formed by the geothermal field, such as sinter. Volcanic formations fill the Tatio graben, including the Miocene Rio Salado ignimbrite and related volcanics which reach thicknesses of in some places, the Sifon ignimbrite, the Pliocene Puripicar ignimbrite and the Pleistocene Tatio ignimbrite; the Puripicar ignimbrite crops out farther west. Active volcanoes in the area include Putana and Tocorpuri.