VOLCANOES OF MEXICO. 25 



4,330 feet in the midst of a nialpah, or pedvegal, a stony tract of lavas enclosed on 

 the south by the Rio Mexcala. Si ace the description given by Humboldt, this is 

 one of the Mexican volcanoes of which most frequent mention is made. Jorullo 

 is commonly supposed to have made its appearance one night towards the end of the 

 year 1759 in the middle of cultivated plains, beneath which long rumbling sounds 

 had been heard for months before the upheaval. Tradition relates that the Cutza- 

 randiro cones, 50 miles to the east, had been in a disturbed state some years before 

 the appearance of Jorullo. Hence the theory that the underground forces opened 

 for themselves another vent by creating the new volcano, and since that time the 

 former craters would seem to have been completely closed. 



This legend, although supported by the immense authority of Humboldt's 

 name, is confirmed by no trustworthy documents, and is, moreover, at vai-iance 

 with the facts since that time observed in every part of the world. One day nothing 

 was visible except a plain covered with sugar-cane and indigo plantations waving 

 in the breeze; next morning six large cones over 1,650 — according to Burkart, 

 1,230 — feet high, presented ihemselves to the astonished gaze of the peasantry, who 

 had taken refuge on the surrounding hills. The whole district was reported to 

 have become, so to say, " embossed," and raised by the molten matter, while the 

 semi-liquid rocks, pierced in the centre by a funnel, were upheaved above their 

 former level to form the cone which is now visible. 



Such an hypothesis of a vertical thrust of the primitive soil is no less absurd 

 than another local statement regarding the vengeance of certain Capuchin friars, 

 who had not been entertained with sufficient honour by the proprietors of the 

 hacienda, and who on their departure consigned the whole district to the de- 

 vouring flames. The formation of Jorullo, like that of all other volcanoes, must 

 in fact be attributed to the ashes and lavas accumulating with each successive 

 eruption. 



Since 1860 Jorullo has been quiescent, or, at least, subject only to slight dis- 

 turbances. From the crater, a yawning chasm over a mile in circuit and 650 feet 

 deep, nothing is now emitted except light vapours, which are mostly invisible, 

 condensing into fog or mist only before rainy weather. The slopes of the mountain 

 have been partly overgrown with forests, in which trees of the tropical are inter- 

 mingled with plants of the temperate zone. Even the hornitos, or " little 

 furnaces," innumerable cones a few yards high, dotted round the base, have also 

 for the most part ceased to discharge jets of vapour. At the time of Humboldt, 

 the temperature of these vapours was 205° F. ; since then it has gradually fallen 

 to from 120° to 140^^ F., within which limits it oscillates at present. The waters 

 have also cooled down in the Rio San Pedro and in another rivulet, which was 

 evaporated or covered by a bed of lava during the eruption, but which reappeared 

 in hot springs several miles from the volcano. 



All these volcanoes, Colima, Tancitaro, Jorullo, and the extinct Tasco, far to 

 the east, but still north of the Rio Mexcala, are disposed in a line parallel with the 

 axis of the Sierra Madre, which runs at a mean distance of about 36 miles north- 

 wards. But this great range is itself composed almost exclusively of old or recent 



