G2G 



ROPY SGORIiE. 



[Ch. XXV 



and Vesuvius, especially near the points from which they 

 issued, exhibiting, for a short distance, flattened spaces a few 

 feet or yards wide, on which the rope-like coils are arranged 



same 



Pig. 66. 



A 



fig. 66. I had an opportunity in 1858 of seeing the manner 

 in which this structure originates. The highest crater of 



steam 



mountain 



Naples 



Ginestr 



"Near 



cently been thrown up. 

 a grotto, from which lava had been flowing without inter- 

 mission for several months, and was still pouring out in a 

 perfectly liquid state. It had built up a ridge between 10 

 and 15 feet in height, at the top of which it had formed 

 a straight canal 5 feet wide. At the point where it issued 



seemed 



white heat. 



me 



movements 



stream 



pierced with small holes through which we looked. 



At the distance of about two yards from the grotto, the 

 lava flowing with great velocity in the canal, began to turn 

 from white to red, and a few feet farther on it acquired a 

 darker colour, and many small separate pieces of scoriae were 

 seen floating on its surface, showing that solidification had 



comm 



efflux 



become 



tached pieces of scoria had begun to be pressed against each 



became 



into continuous ropy coils, each set bending forward in the 



the other, as in fig. 66. 



stream ran fastest, ana ntung one w 



Their successive formation 





it 



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