H 



•^Y 





tli 



a 



*y 



if 



ge^ 



c 



Ui 



11 ianu er 

 rater f 

 but hall 

 lea and 



had 



re- 



iese m 



it inter- 

 out in a 

 ween 10 

 formed 

 it issued 

 ras at a 

 t enough 

 v guides 

 e screen 



otto, the 

 to turn 



quired a 



rise if* 6 



tion Id 



flux 



J 



the 



1 the de- 



jjtft e adl 

 toge*^ 



d iu * 



tion ^ 





e 



Ch. XXV.] 



RECENT DIKES. 



(527 



arrangement reminded me of the manner in which wreaths 

 f foam collect on a river below a cataract or the piers of 



carried by a current or by the wind 



a bridge, 



and being 



a 



some time the marks 



having been formed on the surface one after the other. The 



stream 



The inclined strata 



tion in which such coils are bent. 



Dikes in the recent cone, how formed.— 

 before mentioned which dip outwards in all directions from 

 the axis of the cone of Vesuvius, are intersected by veins or 



most 



number 



them not less than 400 or 500 feet in height, and thinning 

 out before they reached the uppermost part of the cone. 

 Being harder than the beds through which they pass, they 

 have decomposed less rapidly, and therefore stand out in 



re 



lief. 



November 



prevented from descending into the crater by the constant 

 ejections then thrown out ; so that I got sight of three only 

 of the dikes; but Signor Monticelli had previously had 



made 



The 



dikes which I saw were on that side of the cone which is 



encircled by Somma. 



The eruption before mentioned, oi 



November 



ejected matter had filled up nearly one-third of the deep 

 abyss formed at the close of the eruption in 1822. In 

 November I found a single black cone at the bottom of the 

 crater continually throwing out scorise, while on the exterior 

 of the cone I observed the lava of 1822, which had flowed 

 out six years before, not yet cool, and still evolving much 

 neat and vapour from crevices. 



Hoffmann, in 1832, saw on the north side of Vesuvius, 

 near the peak called Palo, a great manv parallel bands of 



Le from < 

 lomerate 



These beds, he says, were cut through 



and augite.* 



is, some of them 

 Somma, the stone being- com 



resemble 



* Geognost. Beobachtungen, &c. p. 182. Berlin, 1839 



s s 2 



