226 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 1 9, 



with the help of the aboTe-meutioned stones a mountam was raised. 

 When on the third day the eruption had ceased for a time, people 

 looked down into the crater and saw the stones boiling up in the 

 middle. The day after, or fourth day, the crater began to throw up 

 again, and on the seventh much more, and some persons were knocked 

 doATu by the stones and killed. 



Falconi's account also alludes to the earthquake and the bui'sting 

 open of the earth, and how ashes and pumice-stones mixed with 

 water were thrown up, and how the sea retired"^. Porzio says, that 

 a large tract of land between Monte Barbaro and the sea near Lake 

 Avernus, was seen to raise itself and of a sudden to assume the form 

 of a growing hill, and in the night this heap of earth {terrcB cumulus), 

 as if opening its mouth, Tomited forth a quantity of fire, pumice-stones, 

 and ashes. 



On comparing all these contemporary statements, I infer that when 

 the ground had first sunk down on the site of the future hill, the 

 lava gradually propelled it upwards again, so that it was distended 

 till it burst. The force of the escaping gases then hurled into the 

 air large fragments of the soil, mixed with mud and pumice, part of 

 which fell back into the boiling gulf, while a part fell over the edge 

 of the crater and contributed to the building up of the cone. We 

 can scarcely expect to find in the walls of such a crater, any consider- 

 able remains of the beds of tuff, which after subsiding and being 

 again elevated must have been much shattered and torn to pieces by 

 the elastic vapom's and incandescent lava shot through them. All 

 the descriptions would lead us to refer the great mass of the hill to 

 the ejected mud and stones, accumulated in the course of a week by 

 the intermittent volcanic action, and I can discover nothing implying 

 such an upheaval of previously solidified and hoiizontal beds of tuff, 

 as might lead us to expect that the walls of the crater would be found 

 to consist of that more ancient formation. Yon Buch indeed is said 

 to have found some marine shells of existing Mediterranean species, 

 hke those which occur in the tuff of Campania, in some of the beds 

 now exposed on the edges of the crater. Such shells may have been 

 ejected in the mud mixed T^ith sea- water which was cast out of the 

 boihng gulf. If however they occur near the bottom of the funnel- 

 shaped hollow, it is possible that some fragments of the original strata 

 which were raised and burst through by the lava and gases may re- 

 main, or some of the huge fragments cast up into the air may well 

 be discoverable in such a position. 



Since writmg the above I have received a memoir on the volcanic 

 region of Campania by Signor Arcangelo Scacchi, published in the 

 Memoirs of the Royal Academy of Naples for 1849, in which he 

 entirely concurs with me in rejectmg the theoiy of upheaval for As- 

 troni, Monte Nuovo, and other cones of that district. The position 

 of the trachyte of the Solfatara and of Astroni are shoTMi to be dif- 

 ferent from what they would have been had the protrusion of the tra- 

 chytic masses been the upheaving cause. 



In regard to Monte Nuovo, Scacchi remarks, that Porzio' s account 

 * Campi Phlegrei, pp. 70, 77. 



