274 



VAL DEL BOVE, ETNA 



XTPPEB 



Gallery. 



Table-case 

 in Recess 6. 



place about 480 B.C., but there is geological evidence to 

 prove that it has been an active volcano for a far greater 

 period. 



The deep valley on the eastern side of Etna, called the 

 Val del Bove, which extends from the woody region nearly 

 to the summit, is especially deserving of notice from the 

 insight it affords into the structure of the entire mountain. 

 (See model.) In the nearly perpendicular precipices, vary- 

 ing from 1000 to 3000 feet in height, which enclose on 

 three sides the great plain forming the Val del Bove, the 

 volcanic beds composed of tuffs, lavas, and breccias, which 

 form its sides, are well displayed. These are pierced in all 

 directions by innumerable vertical dykes, varying in width 

 from two to twenty feet, and composed of trachyte or of 

 compact blue basalt, containing olivine. In consequence of 

 their greater hardness these dykes are better able to resist 

 the disintegrating effects of atmospheric influences than the 

 rocks traversed by them ; they, therefore, waste away less 

 rapidly than the latter, and project from them in vast 

 tabular masses, of various forms, and of great height. 



" There are no records within the historical era which lead 

 to the opinion that the altitude of Etna has materially 

 varied within the last 2000 years. Of the 80 most conspi- 

 cuous minor cones which adorn its flanks, only one of the 

 largest, Monte Rossi, has been produced within the times of 

 authentic history. Even this hill, thrown up in the year 

 1669, although 450 feet in height, only ranks as a cone of 

 second magnitude. Monte Minardo rises even now to the 

 height of 750 feet, although its base has been elevated by 

 more modern lavas and ejections. * * 



To some, perhaps, it may appear that hills of such inco- 

 herent materials, as the loose sand and scoria* of which the 



* 



lateral cones of Etna are composed, cannot be of very great 

 antiquity, because the mere action of the atmosphere must, 

 in the course of several thousand years, have obliterated 

 their orginal forms. But there is no weight in this objec- 

 tion, for the older hills are covered with trees and herbage, 



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