Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/311

Rh larger than the present, and those in the vicinity of Naples, the eruptions of which probably created that district of Italy, are of enormous extent. The crater of the Camaldoli is somewhat more than two leagues in circumference, and the superficies of the Canales is estimated at 12 square leagues. These vast craters were probably capable of ejecting from their bosom those stupendous beds of lava, which being so much more extensive than any that have flowed from more recent eruptions have led some persons to deny the former to be the effects of a central fire. That all the Island of Teneriffe was volcanically produced no man who examines it can have any doubt, and though the smallness of the existing crater of the Peak may lead one to imagine that it alone could not be the effective cause of all the phenomena, yet the innumerable volcanoes on all sides of the island, the appearance of Las Canales, and its elevation, are able to account for the extent of the streams and beds of lava and of the deposits of tufa and pumice, of which the island is composed. Having no data to proceed upon but what is given by the measurement of the eye, it is not easy to determine the magnitude of the cone at its base; one may say at a venture, it is about three miles in circumference, though towards the S.S.W. the descent is much more abrupt, and the plain from which the cone springs not perceptible. The view from the summit is stupendous, we could plainly discover the whole form of the island, and we made out distinctly three or four of the islands, which together are called the Canaries; we could not however see Lancerotte or Fuerteventura, though we were told that other travellers had distinguished them all.

From this spot the central chain of mountains that runs from south-west to north-east is easily to be distinguished. These with the succession of fertile and woody vallies, commencing from San Ursula and ending at Las Horcas, with the long line of precipitous lava rocks