70 
THE PERMIAN VOLCANOES 
BOOK VII 
They are often replete with angular fragments of shale, sandstone 
and limestone, of precisely the same mineral characters as the surrounding 
strata, and containing the same organic remains in an identical state of 
tossilization. It is clear that these strata must have had very much their 
present lithological aspect before the vents were opened through them. 
Again, the necks may often be observed to rise among much contorted 
strata, as, for example, along the crest of a sharp anticlinal arch, or across a 
synclinal basin. The Carboniferous rocks must thus have been considerably 
plicated before the time of the volcanic eruptions. In the next place, the 
vents often occur on lines of dislocation without being affected thereby. 
They must be posterior, however, not only to these dislocations, but also to 
much subsequent denudation, inasmuch as their materials overspread the 
rocks on each side of a fault without displacement. Hence we conclude 
with confidence, that a great deal of volcanic activity in the East of Eife 
must have been posterior to most, if not all, of the Carboniferous period. 
In the neighbourhood of Largo, further important evidence is presented, 
confirming and extending this conclusion. The highest member of the Upper 
Coal-measures, consisting of various red sandstones, with red and purple 
clays, shales, thin coals and ironstones, is prolonged from the Eife coal-field 
in a tongue which extends eastward beyond the village of Lower Largo. It 
is well displayed on the shore, where every bed may be followed in succession 
along the beach for a space of nearly two miles. Two volcanic necks, pre- 
senting the same features as those which pierce the older portions of the 
Fig. 208. — Section in brooks between Bonnytown and Baldastard, Largo. 
a, Sandstone shales and coals of Carboniferous Limestone series ; b, unconformable tuff. 
Carboniferous system to the east, rise through these red rocks. We are 
thus carried not only beyond the time of the Carboniferous Limestone, but 
beyond the close ot the very latest stage of the Carboniferous period in 
Central Scotland. Connected with these and other vents farther north, there 
is a large area of tuff which has been thrown out upon the faulted and 
greatly denuded Carboniferous rocks. It may be traced passing from the 
red Upper Coal-measures across the large fault which here separates that 
formation from the Carboniferous Limestone, and extending inland athwart 
different horizons of the latter series. Outlying fragmentary cakes of it may 
be seen resting on the upturned edges of the sandstones, shales and coal- 
seams, even at a distance of some miles towards the north-west, proving that 
the fragmentary materials discharged from the vents spread over a consider- 
able area. The accompanying section (Fig. 208) may serve as an illustration 
of the relation between this sheet of bedded tuff and the underlying rocks. 
