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634 



ELEVATION CRATERS NOT APPLICABLE 



[Ch. XXV 



I should have been at a loss to account for the support 

 which the theoretical views above stated have received from 

 men of such eminence, had I not been assured by my scien- 

 tific friends at Naples that no one of those geologists ever 

 visited the numerous ravines which intersect the north side of 

 Monte Somma. In exploring these deep and narrow valleys I 

 had the good fortune to be accompanied by Signor Guiscardi, 

 than whom no one possesses a more thorough knowledge of 

 the structure and composition both of Vesuvius and Monte 

 Somma. On looking at the latter mountain from the north, 

 I was struck with its general resemblance to old volcanic 

 cones such as I have seen in the Canary Islands (Palma, for 

 example), or such as Junghuhnhas described in Java. From 

 the crest of the great escarpment of the ' Atrio/ or what the 

 Spaniards would call the ' Caldera,' deep ravines or ' barran- 

 cos/ very near each other radiate outwards in all directions, 

 towards the north-west, north, and north-east, very shallow 

 near the summit, but becoming rapidly deeper and having 

 precipitous sides towards their terminations, as near the towns 

 or villages of Santa Anastasia, Somma, and Ottajano. At the 



upper end of the ravine-like portion of several of these valleys 

 is frequently seen a precipice over which a cascade falls in 

 the rainy season when the channel of the torrent above is full 

 of water. Passing upwards from St. Anastasia into the valley 

 called the Casa delP Acqua, I saw at the head of that ravine 

 a perpendicular cliff, which is the site of one of these water- 

 falls, which was dry at the time. The cliff was 60 feet in 

 height, and consisted of thin beds of stony lava interstrati- 

 fied with others which were more scoriaceous, and some of 

 which were formed of loose pieces of scoriae. At the head of 

 an adjoining ravine called the Eosso di Cancheroni, is a much 

 finer precipice, between 200 and 300 feet high, over which 

 the water is thrown after heavy rains, 

 succession of beds of lava, some of them of a red colour, 

 and much like the modern streams from Vesuvius, divided by 

 strata of scoriae, tuff, and breccia, the latter containing frag- 

 ments of lava often leucitic, sometimes angular, and sometimes 

 rounded by attrition. These last imply that there were 

 gullies of aqueous erosion on the ancient flanks of Somma. 



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