BOILING SPRINGS. 



£67 



with tliose muddy eruptions, which cover large tracts of country with 

 strata containing bituminous or inflammable matter : these strata are 

 as essentially volcanic products, as the matter tlirown out of the vol- 

 cacio of Macaluba in Sicily, which never ejects lava; and we are 

 laence instructed, that one of the substances which promotes volcanic 

 combustion, is bitumen or carbon. The muddy eruptions in the 

 Andes, when first ejected, have little consistence or tenacity ; but 

 they soon become hard, and form what is called by the inhabitants 

 moya ; it is dark coloured and soils the fingers, and is used instead 

 of turf for fuel. 



Boiling springs, and thermal waters, must be classed with volcanic 

 phenomena ; for it can scarcely be doubted, that the Geysers in Ice- 

 land, which, at intervals, throw up columns of boiling water to the 

 height of seventy or eighty feet, are occasioned by the subterranean 

 fires which extend under that island. To the same cause must be 

 ascribed the boiling fountains in the island of St. Michael, one of the 

 Azores. The hot springs in the vicinity of the Pyrenees, in Italy, 

 and in other parts of the world, may with much probability be sup- 

 posed to have a similar' source of heat. The unvaried equality of 

 their temperatures for centuries, proves that this source lies far below 

 the agency of those causes which operate on the surface. It has 

 been remarked, that hot springs are most frequent in volcanic and 

 basaltic countries. Though no active volcano exists in the Py- 

 renees, M. Dralet, in his Description des Pyrenees, says, " that the 

 hot springs and frequent earthquakes in different parts of this chain, 

 offer proofs of the present operation of subterranean fires." I have 

 described the thermal waters of the Alps in the second volume of my 

 " Travels in the Tarentaise," and in Chap. V. p. 68. of the present 

 work. 



However powerful the effects of subterranean fire may be in vari- 

 ous parts of the globe, we must conclude, from the remains of an- 

 cient volcanoes, that in a former period, the action of volcanic fire 

 was far more extensive and intense than at present. 



According to Breislak, an Italian geologist, in a space of twenty 

 miles in length and ten in breadth, between Naples and Cumea, 

 there are no less than sixty craters ; some of them are larger than 

 that of Vesuvius. One of them is two miles in diameter. The city 

 of Cumea, founded twelve hundred years before the Christian era, 

 is built in the crater of an ancient volcano. 



In other parts of Italy, there are undoubted vestiges of ancient vol- 

 canoes. In Sicily, there are a number of extinct volcanoes, beside 

 those connected with jEtna. Many islands in the Grecian Archipel- 

 ago are volcanic. There are remains of large volcanic craters in 

 Spain and Portugal ; and the extinct volcanic mountains in the mid- 

 dle and southern parts of France, cover several thousand square 

 miles. On the eastern banks of the Rhine, and the environs of An- 

 dernach, there are numerous extinct volcanoes. 



