The Chiquimula volcanic field occupies a fault-bounded basin underlain by Cretaceous plutonic rocks in the Chiquimula Valley of SE Guatemala. Initial eruptions during the Pleistocene produced mesa-forming basaltic lava flows along the N-S-trending fault, forming the eastern edge of the Ipala graben. These were followed by the eruption of widespread lava flows NW of Chiquimula town that covered about 12 km2. The most recent eruptions produced basaltic cinder cones and lava flows near the northern edge of Chiquimula town. The cinder cones were constructed along a N-S-trending fracture, with Cerro Grande, the largest, at the northern end and Cerro Chiquito, the youngest, at the southern end. Lava flows from Cerro Chiquito are so fresh in appearance and sparsely vegetated that they were considered by Williams et al. (1964) to be possibly less than 1,000 years old.