THE CRUST OF THE EARTH. 



Val del Bove. 147. Section and plan of Etna. 148. Volcanic lakes. 

 149. Crescent form of volcanic islands. 150. Craters of elevation,, 

 temporary and permanent. 151. Barren island in the Bay of Bengal. 

 152. Traditional volcanic origin of Santorin. 



129. THE famous volcano of Jorullo in the Anahuac mountains 

 in Mexico had its origin in similar phenomena. The elevated 

 plateau which forms the province of Quito, in South America, has 

 been the theatre of extraordinary volcanic phenomena. Beneath 

 it is a focus of volcanic energy, the channels of which communi- 

 cate with the atmosphere by the craters of the great volcanoes of 

 Pichincha, Cotopaxi, and Tunguragua, part of the chain of the 

 Andes. These, by their groupings as well as by their lofty eleva- 

 tion and grand outlines, present the most sublime and picturesque 

 aspect which is anywhere concentrated within so small a space 

 in a volcanic landscape. The extremities of the chain are con- 

 nected by subterranean communications; and this fact, which 

 experience has made known to us in numerous instances, reminds 

 us of the old and just statement of Seneca, that the crater is only 

 the issue of more deeply-seated volcanic forces. 



130. The Mexican volcanoes of Orizaba, Popocatapetl, Jorullo, 

 and Colima also appear to be connected with each other, being 

 placed in the direction of a line running transverse to the former, 

 and passing east and west from sea to sea. 



131. As was first observed by Humboldt, these mountains are 

 all situated between north latitude 18 59' and 19 12'. In an 



Fig. 53. Volcano of Jorullo, Mexico. 



exact line of direction with the other volcanoes, and over the 

 same transverse fissure, Jorullo was suddenly elevated on the 

 93 



