1856.] SCROPE CRATERS AND LAVAS. 331 



of the prodigious distances to which ashes, and even large fragments 

 of lapillo and of pumice, have been occasionally borne away from 

 some of the volcanoes of South America and the Pacific (as, for ex- 

 ample, in the eruption of Coseguina in 1835, and of Galongoon in 

 1822), — distances of more than a thousand miles (a large segment 

 of the circumference of the globe), the whole of which intermediate 

 space must have been strewn with them (and, in the first of these 

 instances, it is said, to the depth of ten feet at the distance of twenty- 

 four miles from the volcano), we may well conceive that eruptions 

 productive of such an enormous amount of ejected matters may (nay, 

 must) have blown into the air entire mountains of a magnitude far 

 exceeding that of Vesuvius and Somma itself, or the bulk of matter 

 wanting in the Val di Bue, and left in their place craters of corre- 

 sponding dimensions. 



Sir Charles Lyell suggests (as others have done before him), in 

 regard to some of the largest known craters, another possible origin, 

 which he calls Engulfment — that is, the subsidence of the upper 

 part, or a large area, of a volcanic mountain into some abyss suddenly 

 opened beneath. With respect to this supposition, without attempt- 

 ing to dispute its possibility, I must say that I am not aware of any 

 such process having been ever witnessed by any credible observer so 

 placed as to be able to distinguish between engulfment and ejection ; 

 and consequently that it were well to be cautious in admitting the 

 occurrence of such a phsenomenon, if the ordinary mode of action 

 be sufficient to explain the facts really observed. We possess reports, 

 it is true, of eruptions and earthquakes in Java, Sumatra, the Andes, 

 and elsewhere, having caused the disappearance of the entire summit 

 of a mountain, leaving a vast cavity in its place. But this is pre- 

 cisely the result that was observable after the eruption of Vesuvius 

 in 1822. And in that instance we know there was no subsidence. 

 The leading example usually adduced of such immense (supposed) 

 engulfments is the truncation of the lofty cone of Papandayang, in 

 Java, by an eruption in the year 1772. There, it is always said, a 

 great area of the volcano " fell in and disappeared," swallowed up in 

 the bowels of the earth, together vdth forty villages and their inha- 

 bitants. Such are the phrases usually made use of on these occasions, 

 and very naturally so, by alarmed and unscientific observers. But 

 recent explorers, especially Professor Junghuhn, have stated that 

 these towns and villages of Papandayang were not swallowed up at 

 all, but buried, like Pompeii, under the ejectamenta of the volcano ; 

 and Dr. Junghuhn, therefore, very properly refers the truncation of 

 the mountain to eruptive explosions, rather than to subsidence. 



It is, no doubt, quite conceivable, that within a volcanic mountain 

 some internal reservoir, or subterranean lake of liquified lava, coated 

 over by a crust of hardened rock or the accumulation of fragmentary 

 matter, may be tapped, as it were, by an earthquake, and empty 

 itself out of an aperture in the side of the mountain at a low level, 

 leaving a cavity, which another earthquake, or the explosion of vapour 

 and gases accumulated within it and increasing in temperature, may 

 cause to burst, like a vast bubble, — the overlying crpst of rocks 



VOL. XII. — PART I. 2 A 



