OP VOLCANOS. 381 



have probably been raised from a fissure of 420 English geographi- 

 cal miles long, traversing the Continent from the Pacific to the 

 Atlantic Ocean. 



These assemblages of volcanos, whether in rounded groups or in 

 double lines, show in the most conclusive manner that the volcanic 

 agencies do not derjend on small or restricted causes, in near 

 proximity to the surface of the earth, but that they are great phe- 

 nomena of deep-seated origin. The whole of the eastern part of 

 the American Continent, which is poor in metals, is, in its present 

 state, without fire-emitting mountains, without masses of trachyte, 

 and perhaps even without basalt containing olivine. All the Ame- 

 rican volcanos are on the side of the Continent which is opposite to 

 Asia, in the chain of the Andes which runs nearly in the direction 

 of a meridian, and extends over a length of 7200 geographical 

 miles. 



The whole plateau or high-land of Quito, of which Pichincha, 

 Cotopaxi, and Tunguragua form the summits, is to be viewed as a 

 single volcanic furnace. The subterranean fire breaks forth some- ' 

 times through one and sometimes through another of these open- 

 ings, which it has been customary to regard as separate and distinct 

 volcanos. The progressive march of the subterranean fire has been 

 here directed for three centuries from north to south. Even the 

 earthquakes which occasion such dreadful ravages in this part of 

 the world afford remarkable proofs of the existence of subterranean 

 communications, not only between countries where there are no 

 volcanos (a fact which had long been known), but also between fire- 

 emitting openings situated at great distances asunder. Thus in 

 1797 the volcano of Pasto, east of the G-uaytara River, emitted 

 uninterruptedly for three months a lofty column of smoke, which 

 column disappeared at the instant when, at a distance of 240 geo- 

 graphical miles, the great earthquake of Riobamba a'nd the immense 

 eruption of mud called " Moya" took place, causing the death of 

 between thirty and forty thousand persons. 



The sudden appearance of the Island of Sabrina near the Azores, 

 on the 30th of January, 1811, was the precursor of the terrible 

 earthquake movements which, much farther to the west, shook 

 almost incessantly, from the month of May, 1811, to June, 1813', 



