28 
the carboniferous volcanoes 
BOOK VI 
“ Lr^ - ,x b "“ d 
i« the limestones, and showing no T ' * S 
to the detritus of once living organisms ' lts P rese “«' 
-sit" tttt st;: t i? 
pass into a coarse slag. They vary un t/*W flT K d sometlmes 
sSrSyfforS'vSd^ 6 beende f Ved from ^ S^tionofLadr 
and irregular in the centre of the 11 | 0 ' veiter ’ tlie cavities are large 
smaller aud a* ^ ^ ** ™ 
m true volcanic bombs. } 1 lcal sha P e of tho mass, as 
The limestone fragments enclosed in tho +,,«■ • i i 
carbonaceous and of the pale encrinal varieties, fnto caSetd ** 
any sensible alteration of these fragments ti, i f dld 1 observe 
from material disrupted and elected In ,, ' ' fco have ljl ' e " derived 
and not to have bt evtt for g - “ he “W' successive vents. 
...fluence of volcat Vttt %£”"**•* *“ “> *>“ 
the MeTCnt forttatt’”' “ *<W «* sonth coast of 
which the tuffs were ejected ' A pi6SeiVe or us some of the vents from 
number, mag be IrZd lZt at F* «"» « *-» in 
hue from sLlet Point I ST*™?- “ d *** 
some places exceedingly well defined Tim ( i •, • margins are m 
feature occurs in the “nLt wet" nt whi «* 
t^agglomemte rta verfctll, thmugl, 
be drawn between the liiaterffftm^tteiit md*Srof”a ShMI ’ ““ 
tuffs. Hence it is difficult to define precisely the f I 16 SUrroundin g 
lam inclined to believe from this in -ini n °im and size of the vents. 
remarkable structure of the dykes, to which TThall '."ft 1116 ’ ^ 'T" the 
the presently visible parts of these necks must lie , f e ™ ls refer > that 
blocks of lava, too resemble in e P > u felspar- crystals. The large 
tuffs^bnt greatly exceed them in leu^Zu^T" ^ * ** ^ 1 
rf limestone. 
Lamplugh have mapped a lame n,,,™ J v . ° rviessrs. Strahan and 
PP a large mass of limestone at the Scarlet vent, which. 
