212 On the Vents of Hot Vapor in Tuscany. 
point at which the water issued. These appearances not only 
served to explain the origin of the larger muddy bosses of similar 
form, common in the incoherent subsoils of Calabria, which have 
been so frequently subject to great earthquakes, but may also be 
viewed as another link which connects the present small disturb- 
ances of the surface, with the former powerful subterranean en- 
ergy proceeding from igneous and gaseous development we have 
been considering. 
Thus, in reference to my preceding memoirs and in reasoning 
by analogy, we are led to infer, that the great evolution of molten 
matter in former or plutonic times, accompanied by so much heat 
and its gaseous attendants as to metamorphose whole mountain 
chains, was succeeded, as the bottoms of the sea rose, by a con- 
siderable diffusion of volcanic materials, chiefly of subaqueous 
origin, but in part subaérial ; and that, finally, the lands assuming 
their present relations to the sea, the extension of molten matter 
has been confined to a very limited number of fissures or vents 
of eruption, many of which have become extinct with the lapse 
of time. A portion, however, of these eruptions in Europe is 
still in continuous activity, whether in emitting solid matter, as 
at Stromboli, or hot springs and vapors, as in the Tuscan Soffioni ; 
whilst another portion is intermittent, as viewed in the paroxysmal 
outpourings of Etna and Vesuvius, the occasional formation of 
ll new cones and craters under the waters of the Mediterra- 
nean and the fitful lines of earthquake shocks with their accom- 
panying outbursts of water. 
In viewing the intimate connection between all these phenom- 
ena, and in looking to the powers of the Soffioni of Tuscany, we 
might perhaps infer, that if these gusts of heat were entifely re- 
pressed by closing up the orifices through which they now escape, 
earthquakes to some slight extent might be expected still more to 
prevail in the neighborhood, until the expansive forces were libe+ 
rated ; just as the most calamitous shocks in Sicily and Calabria 
have occurred when Etna has been most dormant. Putting aside 
this speculation, the hot vapors may unquestionably be viewed as 
the remains of former igneous action, which I believe to have 
been incalculably more powerful, not only because it is on the 
same band or its subordinate parallels that the copious masses of 
plutonic rocks of this tract and the adjacent mineralized strata 
occur, but because this line is absolutely coincident with the axis 
of the Carrara and other marbles and their associated slates and 
crystalline rocks of the Apuan Alps. Now, as those lofty masses 
or western Appennines, together with their lower parallels in the 
Gulf of La Spezia, have been shown to be simply altered strata 
of jurassic age*; so in extending our observation in the same line 
OE ae ite college 
* See Quart. Journ. Geol. Soc., vol. v, p. 266 et seq. 
