ISOLATED POSITION OF VOLCANOES. 
91 
appear still more isolated, more variable, n ore obscure, than 
we imagine tbem when consulting the narratives of travellers. 
These reflections occurred to me on descending from the 
summit of the peak of Teneriffe, the first unextinet volcano 
I had yet visited. They returned anew whenever, in South 
America, or in Mexico, I had occasion to examine volcanic 
mountains. When we reflect how little the labours of 
mineralogists, and the discoveries in chemistry, have pro- 
moted the knowledge of the physical geology of mountains, 
we cannot help being affected with a painful sentiment; and 
th.is is felt still more strongly by those, who, studying 
nature in different climates, are more occupied by the pro- 
blems they have not been able to solve, than with the few 
results they have obtained. 
The peak of Ayadvrma, or of Echcyde,* is a conic and 
isolated mountain, winch rises in an islet of very small cir- 
cumference. Those who do not take into consideration 
the whole surface of the globe, believe, that these three 
circumstances are common to the greater part of volcanoes. 
They cite, in support of their opinion, Etna, the peak of the 
Azores, the Soltiitara of Guadaloupe, the Trois-Salazes of 
the isle of Bourbon, and the clusters of volcanoes in the In- 
dian Sea and in the Atlantic. In Europe and in Asia, as far 
as the interior of the latter continent is known, no burning 
volcano is situated in the chains of mountains; all being at 
a greater or less distance from those chains. In the New 
World, on the contrary, (and this fact deserves the greatest 
attention,) the volcauocs the most stupendous for their 
masses form a part of the Cordilleras themselves. The 
mountains of mica-slate and gneiss in Peru and New Gre- 
nada immediately touch the volcanic porphyries of the pro- 
vinces of Quito and Pasto. To the south and north of these 
countries, in Chile and in the kingdom of Guatimala, the 
active volcanoes are grouped in rows. They are the conti- 
nuation, as wo may say, of the chains of primitive rocks , 
and if the volcanic lire has broken forth in some plain remote 
from the Cordilleras, as in mount Sangay and Jorullo,t we 
* The word Echeyde, which signifies Hell in the language of the 
Guanclies, has been corrupted by the Europeans into Teyde. 
+ Two volcanoes of the Provinces of Quixos and Mechoaean, the oni 
H > the southern, and the other in the northern hemisphere. 
