The composite late-Pleistocene Calabozos caldera (14 x 26 km) produced major rhyodacitic-to-dacitic ashflow sheets of ~200-500 km3 each, collectively referred to as the Loma Seca Tuff, at 800,000, 300,000, and 150,000 years ago. Eruptive activity has continued into the Holocene, forming the 20-25 km3 and the four clustered vents of Descabezado Chico near the western caldera rim. The late-Holocene 2.5 km3 Escorias dacitic lava flow from Descabezado Chico traveled more than 30 km S. Several hot-spring clusters are present along the margin of the central resurgent uplift within the caldera.