The massif delimits the Salar de Maricunga and has an extent of . The principal edifices are small but steep, rising above their bases. The northern cone is glacially eroded and has a crater wide. The central edifice has a crater and is inclined westward. The southern edifice is formed from an older western structure (0.8±0.5 mya) with two small craters and a glacial cirque, and an eastern edifice with a summit lava dome wide and basal lava flows. A cirque cuts the dome on the southeastern side and contains a small glacier. The whole edifice and the adjacent Miocene El Plateado volcano, as well as the western flank of neighbouring Ojos del Salado volcano, are covered with a thick layer of pumiceous ash fall, probably produced by the collapse of an eruption column. Pliocene volcanic chain Cristi (2.5±1.3 mya), Lemp (2.8±0.3 mya) and Rodrigo (adakites 4.4 mya) north and Puntiagudo south is largely buried beneath the massif. Tomographic analysis of the area has indicated the presence of a large high-attenuation zone in the crust beneath Tres Cruces and the neighbouring Ojos del Salado volcano, which may indicate ongoing or incipient melting of the underlying crust.