Las Cumbres is
an eroded stratovolcano consisting of thick and massive hornblende-bearing
andesitic lava flows. The present summit rim (3,800 m asl) marks the boundary
of a 4 km diameter collapse caldera that is breached to the east. The maximum
height of the pre-collapse stratovolcano could have been similar to that of
the present Citlaltépetl volcano (5675 m asl) because these two volcanoes
have a similar base diameter of about 20 km.
