 Calabozos is a ring @-@ shaped caldera 26 kilometres ( 16 mi ) by 14 kilometres ( 9 mi ) wide , with an elevation of 3 @,@ 508 metres ( 11 @,@ 509 ft ) . Volcanoes have been formed by eruptions in the crater . The largest , which is on the southern rim of the caldera , is the Holocene Cerro del Medio complex with an elevation of 3 @,@ 508 metres ( 11 @,@ 509 ft ) . It is made mainly of andesite and dacite , and has a volume of 20 cubic kilometres ( 5 cu mi ) to 25 cubic kilometres ( 6 cu mi ) . On the southwestern edge several eruptions have created the Descabezado Chico volcano ( elevation : 3 @,@ 250 metres ( 10 @,@ 663 ft ) ) which consists of four overlapping volcanic craters . The last eruption occurred during Holocene time , and produced a dacitic lava flow ( 2 @.@ 5 cubic kilometres ( 1 cu mi ) in volume ) that extends for 30 kilometres ( 19 mi ) . Cerro Colorado , with an elevation of 2 @,@ 928 metres ( 9 @,@ 606 ft ) , forms another cone in the complex . 
