Ch. IX.] 
SUBAQUEOUS FORMATIONS HOW RAISED. 
105 
proached the small town of Tripergola, emitting a vivid light, 
and throwing out ignited sand and scoriae. At length this 
opening reached a shallow part of the sea close to the shore, 
and then widened into a large chasm, out of which were dis- 
charged blocks of lava, pumice, and ashes. But no current 
of melted matter flowed from the orifice, although it is perfectly- 
evident that lava existed below in a fluid state, since so many- 
portions of it were cast up in the form of scorise into the air. 
We have shown that the coast near Puzzuoli rose, at that time, 
to the height of more than twenty feet above its former level, 
and that it has remained permanently upheaved to this day *. 
On a review of the whole phenomena, it appears most pro- 
bable that the elevated country was forced upwards by lava 
which did not escape, but which, after causing violent earth- 
quakes, during several preceding months, produced at length 
a fissure from whence it discharged gaseous fluids, together 
with sand and scoriae. The intruded mass then cooled down 
at a certain distance below the uplifted surface, and consti- 
tuted a solid and permanent foundation. 
If an habitual vent had previously existed near Puzzuoli, 
such as we may suppose to remain always open in the principal 
ducts of Vesuvius or Etna, the lava might, perhaps, have 
flowed over upon the surface, instead of heaving upwards the 
superficial strata. In that case, there might have been the 
same conversion of sea into land, the only difference being, that 
the lava would have been uppermost, instead of the tufaceous 
strata containing shells, now seen in the plain of La Starza, and 
on the site of the Temple of Serapis. 
Subterranean lava the upheaving cause. — The only feasible 
theory, indeed, that has yet been proposed, respecting the 
causes of the permanent rise of the bed of the sea, is that 
which refers the phenomenon to the generation of subterranean 
lava. We have stated, in the first volume, that the regions 
now habitually convulsed by earthquakes, include within them 
the site of all the active volcanos. We know that the expan- 
* Vol, i. chap. xxv. 
