East of Tunupa lie the Huayrana lavas, which are much older (Potassium-argon dating has yielded an age of 11.1 ± 0.4 million years ago). Tunupa and Sillajhuay farther west form a chain of volcanoes known as the Serranía Intersalar, which lies within the so-called Pica gap where recent volcanism is rare. This chain of volcanoes was active starting from the Oligocene to the Quaternary.