ON ITS EXTERIOK. VOLCANOES. 299 



well as the Cerro del Mirador and the high mountain 

 masses whose curve bounds the plain to the east- 

 ward, to be regarded as having existed before the 

 catastrophe. 



I have still to describe the great fissure over which six 

 volcanoes (not touching each other) have been raised, in 

 a direction running generally from S.S.W. to N.N.E., 

 but in the three southernmost almost S. to N. The fissure 

 (1700 toises in length) is therefore a little curved ; its 

 general direction is almost perpendicular to that which 

 I have assigned to the volcanoes of Mexico, taken from 

 sea to sea. Such differences need not excite surprise, 

 inasmuch as the partial relations of a single group, and 

 those of the great masses across an entire continent, 

 ought not to be confounded. Thus, the long ridge of 

 Pichincha has not the same direction as the system of 

 the Quito volcanoes ; and in non-volcanic chains, e. g. in 

 the Himalaya, the highest points are often far from 

 being situated in the general elevation-line of the chain, 

 being instead, on shorter snowy ridges, almost at right 

 angles to it. 



Of the six volcanic hills raised over the fissure above 

 spoken of, the three southernmost, between which the 

 route to the copper mines of Inguaran passes, are in their 

 present state the least interesting. They are no longer 

 open, and are entirely covered with greyish-white vol- 

 canic sand, not consisting, however, of pumice, of which, 

 or of obsidian, I saw no signs in this district. At Jo- 

 rullo, as at Vesuvius according to the statements of Von 

 Buch and Monticelli, the last and covering fall of ashes 

 seems to have been the white one. The fourth mountain 

 (going northward) is the great and proper volcano of 



