Two intersecting volcanic chains, the Cordón de Puntas Negras and Cordón Chalviri, trend roughly SE from Chiliques volcano to Volcán Puntas Negras stratovolcano and SW from there to Cerro Tuyajto, respectively. The chain of small cones, lava domes, lava flows, and maars covers an area of about 500 km2 and contains at least 25 different vents. The Cordón de Puntas Negras is situated along the southern margin of the 35 x 70 km Pliocene La Pacana caldera. The pristine morphology of many of the volcanic features indicates a Holocene (de Silva and Francis, 1991) or historical (González-Ferrán, 1995) age. Small cones such as Cerros Cenizas, Aguas Calientes, Laguna Escondida, and Chinchilla have well-preserved summit craters and produced short lava flows. A distinct maar-type vent is present, as well as a 13 km2 silicic lava flow and dome complex. A volcanic center immediately SE of Cerro Laguna Escondida appears to be the youngest vent of the complex.