"Six volcanic cones, composed of scoriæ and fragmentary lava, were formed on the line of a chasm which ran in a direction from N. N. E. to S. S. W. The least of these cones was 300 feet in height, and Jorullo, the central volcano, was elevated 1,600 feet above the level of the plain. It sent forth great streams of basaltic lava, containing included fragments of rocks, and its ejections did not cease till the month of February, 1760.
"Humboldt visited the country more than forty years after this occurrence, and was informed by the Indians, that when they returned, long after the catastrophe, to the plain, they found the ground uninhabitable from the excessive heat. When he himself visited the place, there appeared around the base of the cones, and spreading from them, as from a centre, over an extent of four square miles, a mass of matter of a convex form, about 550 feet high at its junction with the cones, and gradually sloping from them in all directions towards the plain. This mass was still in a heated state, the temperature in the fissures being on the decrease from year to year, but in 1780 it was still sufficient to light a cigar at the depth of a few inches. On this slightly convex protuberance, the slope of which must form an angle of about 6° with the horizon, were
