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C. Darwin, Esq., on Volcanic 



reckoned as unity ; on such a coast it ceases to be improbable, in any ex- 

 cessive degree, that the many impulses which together have produced the one 

 grand effect, should sometimes have been absolutely simultaneous. 



It has long been remarked, that the vents throughout the Cordillera may be 

 grouped into several systems. Thus we have already shown, that the extreme 

 southern volcanos are connected with those of Central Chile; and I was in- 

 formed by an intelligent resident that he had seen Aconcagua and two vol- 

 canos northward of it, in great activity together: — we thus have a portion of 

 the Andes 780 geographical miles in length (about the distance from the south 

 of England to Vesuvius) forming one connected system. Ulloa * states, that 

 when Lima was overthrown in 1746, three volcanos near Patas and one near 

 Lucanas burst forth ; these places being 480 miles apart from each other. 

 Moreover, Arequipa, to the south, has twice (1582 and 1687) been affected 

 by severe earthquakes simultaneously with Lima. The distance between 

 Arequipa (where there is an active volcano) and Patas is rather more than 

 600 miles; and this perhaps may form a second system. 



Humboldtt says, " it appears probable that the higher part of the kingdom 

 of Quito, and the neighbouring Cordillera, far from being a group of distinct 

 volcanos, constitute a single swollen mass, an enormous volcanic wall stretch- 

 ing from north to south, and the crest of which exhibits a surface of more 

 than six hundred square leagues. Cotapaxi, Tunguragua, Antisana, and Pi- 

 chincha, are placed in this same vault, on this raised ground." He after- 

 wards shows, from the phenomenon already alluded to, of the cessation of the 

 column of smoke at the moment when Riobamba was overthrown, the con- 

 nexion of these volcanos with those of Pasto and Popayan. This joint system 

 is rather less than 300 miles in length. Again, to the north at Guatimala, 

 Mexico, and California, we have three groups of volcanos, each system being 

 a few hundred miles apart. 



The connexion between the vents in each separate system has been, in 

 some places, plainly shown, and is extremely probable in all ; but what relation 

 the different systems bear to each other is more doubtful. 1 am not aware of 

 any fact on record, similar to the contemporaneous eruption of Osorno and 

 Aconcagua with Coseguina. It must not, however, be overlooked, that such 

 events may have happened every year since the Spanish conquest, without the 

 coincidence having once been detected. Excepting from the concurrence of 

 two accidents, I should never have known of this case. On that same night 

 every vent in the Cordillera might have shown transient signs of activity, 

 and six months afterwards it would have been as impossible to have discovered 



* Ulloa's Voyage, English Translation, Vol. ii. p. 84. 

 f Personal Narrative, Vol. iv. p. 29. 



