The base that Tutupaca rises from lies at elevations ranging from to and the volcano covers a surface area of about . The older complex is formed mainly by lava flows, which during the Pleistocene were eroded by glaciers forming up to thick moraines and U-shaped glacial valleys. Cirques and moraines are also found on the western summit, and tephra layers extend west of the volcano. The older complex, which includes lava domes in the form of small hills on its southern part, was the source of ignimbrite that covers the western and southern parts of the volcano. Postglacial lava flows emanating from a vent located between the two peaks have been identified.