“ On the southern slope, at a height of 15,059 ft., is a bare cone of porphyritic andesite called El Picacho, “the beak,” or Cabeza del Inca, “the Inca’s head,” with dark cliffs rising fully 1000 ft., which according to tradition is the original summit of the volcano blown off at the first-known eruption of 1532. The summit of Cotopaxi is usually enveloped in clouds; and even in the clearest month of the year it is rarely visible for more than eight or ten days. Its eruptions produce enormous quantities of pumice, and deep layers of mud, volcanic sand and pumice surround it on the plateau. ”