Cn 



. XXIII.] 



OF VOLCANIC REGIONS 



579 



VOLCANIC REGIONS. 



'i 

 it 



i 



)/ South America — Of these great 



regions, that of the Andes of South America is one of the 

 best denned ; it affords an illustration of the linear arrange- 



m 



exem 



are 



canos 



cation in Europe, where the most active volcanic vents 

 isolated. If we turn first to that part of the Cordillera 

 which extends from lat. 2° N. or northward of Quito to lat. 

 43° S. or southward of Chili, we have, in a space compre- 

 hending forty-five degrees of latitude, an alternation on a 

 grand scale of districts of active with those of extinct vol- 

 , or which, if not spent, have at least been dormant for 

 the last three centuries. How long an interval of rest may 

 entitle ns to consider a volcano as entirely extinct is not 

 easily determined ; but we know that in Ischia there inter- 

 vened between two consecutive eruptions a pause of seven- 

 teen centuries ; and the discovery of America is an event of 

 far too recent a date to allow us even to conjecture whether 

 different portions of the Andes, nearly the whole of whicl 



are subject to earthquakes, may not experience alternately a 

 cessation and renewal of eruptions. JSTor does the linear 

 series seem to end even with the southern limits of the 

 Cordillera, for we can scarcely doubt that the Fuegian vol- 

 canos in lat. 54° 30' S., and those of South Shetland, lat. 61° 



same 



The principal line of active vents which have been seen in 

 eruption in the Andes extends from lat. 43° 28' S. ; or, from 

 Yantales, opposite the isle of Chiloe, to Coquimbo, in lat. 30° 

 o. ; to these thirteen degrees of latitude succeed more than 

 eight degrees, in which no recent volcanic eruptions have 

 been observed. We then come to the volcanos of Bolivia 



om 



1ST., or from 





S. to lat. 15° S. Between the Peruvian volcanos and 



^se of Quito, another space intervenes of no less than 



fourteen degrees of latitude, said to be free from volcanic 



action so far as yet known. The volcanos of Quito then 



su cceed, beginning about 100 geographical miles south of 



P p 2 



