CARBONIFEROUS VOLCANIC ROCKS OF THE FIRTH OF FORTH BASIN. 471 
black chips. So far as can be ascertained from the slices already prepared for 
the microscope, the wood is always coniferous. These woody fragments have not 
been found in the interstratified tuffs nor in the associated strata. They are speci- 
ally characteristic of the necks. The trees from which they are derived grew, 
I believe, on the volcanic cones, which as dry insular spots would support a 
different vegetation from the club-mosses and reeds of the surrounding swamps. 
As the fragments occur in the tuffs which, on the grounds already stated, may 
be held to have been deposited within the crater, they seem to point to 
intervals of volcanic quiescence when the dormant or extinct craters were filled 
with a terrestrial flora, as Vesuvius was between the years 1500 and 1631, when 
no eruptions took place. Some of the cones, such as Largo Law, the Saline 
Hill, and the Binn of Burntisland, no. doubt rose several hundred feet above the 
water. Clothed with dark pine woods, they must have formed a notable feature 
in the otherwise monotonous scenery of central Scotland during the Carboni- 
ferous period. 
Relation of the visible Necks to the position of the original Volcanic Cones and 
the surrounding Sheets of Lava and Tuf—F¥rom the facts above detailed, it is 
evident that in most cases the necks represent, as it were, the mere denuded 
stumps of the volcanoes. In some cases, indeed, denudation has not advanced 
so far as to lay bare the cones, which still consequently lie buried under 
subsequent accumulations. There must be many concealed cones of this kind 
in the region. In a few examples the progress of denudation has reached such 
a point that the cone can be partially made out amidst its surrounding masses 
of tuff. One of the most interesting of these is Largo Law, of which an outline 
has been given in fig. 2. The accompanying section (fig. 13) represents what 
=. Rin BI» ze 
A 
NT 
LM 
ti TIANA ne 
Fig. 13.—Section across Largo Law. 
1, 1, Lower Carboniferous strata ; ¢, Tuff of cones; ¢’, Tuff of plain beyond the cones; BB, Basalt ascending 
vents and sending out veins ; B’, Basalt which has probably flowed out at the surface. (See p. 467.) The dotted 
lines are suggestive of the original outline of the hill. 
appears to me to be the structure of this hill. There are two conjoined cones, 
each of which was probably successively the vent of the volcano. The southern 
and rather lower eminence, as already mentioned, is traversed by rib-like dykes 
of basalt, which point towards its top, where there is a bed of the same rock 
underlying a capping of tuff. On its eastern declivity lies the basait coulée, 
