 The first phase of activity involved the formation of calderas and stratovolcanoes; later during the ice ages lava flows and ignimbrites were emplaced.Finally, the present stratovolcano with its caldera was emplaced towards the end of glaciation; parasitic vents formed even later and produced lava flows.Quetrupillán has erupted pyroclastics, which have formed flow and pumice deposits east of the volcano.