 Incapillo is a caldera with a diameter of 5 by 6 kilometres ( 3 @.@ 1 mi × 3 @.@ 7 mi ) at an elevation of 5 @,@ 750 metres ( 18 @,@ 860 ft ) . The three adjacent volcanic centres of Monte Pissis ( 6 @,@ 882 metres ( 22 @,@ 579 ft ) ) , Cerro Bonete Grande ( 6 @,@ 436 metres ( 21 @,@ 115 ft ) ) , and Cerro Bonete Chico ( 6 @,@ 759 metres ( 22 @,@ 175 ft ) ) are also considered part of this volcanic complex and are among the highest on Earth . These centres surround the ignimbrite and lava domes . The walls of the caldera are 250 metres ( 820 ft ) high . A uniform ignimbrite , called the Incapillo ignimbrite , is rich in pumice and forms the bulk of the caldera walls . 
