On the Venis of Hot Vapor in Tuscany. 199 
Arr. XXIV.—On the Vents of Hot Vapor in Tuscany, and 
their relations to Ancient Lines of Fracture and Eruption ; by 
Sir Ropericx Impry Murcurison, G.C.St.8., F.R.S., G.S., L.8.* 
Introduction —In surveying the principal localities of those 
remarkable vents of hot vapor in the Tuscan Maremma, called 
“Lagoni,” “Fumacchi,” ‘“Fumarole,” “Soffioni,” ‘ Mofetti,” 
and even “ Voleani,”} I perceived that their issue took place upon ~ 
ancient parallel lines of fracture, along which serpentinous and 
other eruptive rocks had been emitted. As Iam not aware that 
this coincidence in lines of eruption, acted upon at epochs so re- 
mote from each other, has been previously adverted to in any 
geological account of Tuscany, I will first call: attention to the 
phenomenon. I shall next take this opportunity of expressing 
my opinion respecting the origin of the ‘“gabbro rosso” of the 
Tuscans, a rock intimately associated with serpentine ; and, after 
a brief allusion to recent earthquake shocks along the same lines, 
the memoir will be terminated by glancing at the simultaneous 
production of great divergent elevations in Italy and in the Alps, 
after the deposit of the nummulitic eocene formation. ¥ 
_ Hot vapor vents.—If the intensely hot vapor gusts which have 
issued for centuries from cavities in the rocks of the Tuscan Ma- 
remma had been as well known to Dante, as they were to Tar- 
gioni Tozzetti their graphic describer in the last century, the 
great poet would surely have selected them as a finer illustration — 3 
of infernal agency than the feeble “ bullicami” of Viterbo.t In 
our own day the chief features of the Tuscan escapes of hot 
* From the Quart. Journ, of the Geological Society, vi, 367, November, 1850. 
agoni, see Gio. 
t For Italian descriptions of the L Gio. Targioni Tozzetti, Viaggi; 
“ petit, Dictionario ik ay &c. della Toscana, tom. iii, p. 369; Bartolini, Kitrded 
heaton gg tom. vi, p. 335; Mascagni, Commentario (Siena), 1779: Guerrazz, Con- 
= dei Georgofili, tom, ii, p. 435; and Repetti, Dizion. fisic. stor. ec. della Toscana, 
Sor 624, tom. iii, p. 874, and Continov. degli Atti dei Georgofili, tom, xi, p. 49- 
; See Lyell’s Diicditiow of Geology, 7th ed. p. 243. 
Quarterly Journal of the Geological Society, vol. i, p. 296 
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