National Geographic : 1916 Jul
POPOCATEPETL FROM THE SUMMIT OF THE IXTACCIHUATL This graceful extinct volcano rises more than three miles above the level of the sea. AccordingtoIndian traditions, itcame into being after a violent earthquake following terrific subterranean noises. It has been quiescent since 1802. Statisticians estimate that Ioo,ooo,ooo pounds ofsul phur have been removed from it since the Conquest.