Mount Jorutto, in Mexico, affords a curious illustration of volcanic action combined with extensive elevation. This vast mountain rises in the great plain of Malpays, which up to June, 1759, was never suspected to be the site of a volcano, although the basaltic hills of the neighbourhood clearly indicate that the district had at some very early period been the theatre of volcanic eruptions, which had filled up the original valleys.
In the month of June, 1759, hollow murmurings began to be heard, speedily attended by earthquakes, which followed each other in rapid succession up to the month of September. The surface-soil at last swelled up like a large bladder, three or four miles square; it finally burst open in various parts, flames issuing forth through the fissures, and burning fragments of rocks being thrown up high into the air. Six conical vents were thus formed in different parts of the area, of which the lowest was 800 feet high. Besides these, thousands of small cones or bosses arose, which cracking subsequently emitted aqueous and sulphureous vapours. These bosses are called in the country Hornitos, or small ovens.
Towards the close of the month of September, the vast mountain Jorullo was pushed up bodily in a few days, by the subterranean force, to an elevation of 1682 feet above what had been a plain up to the preceding month of June. The crater of Jorullo threw out immense streams of basaltic lava, which continued to flow till February, 1760, after which
