56 
THE PERMIAN VOLCANOES 
BOOK VII 
intercalation of the volcanic series in the .red sandstones is well displayed, 
we enter, extensive tracts where these inters tra tilled rocks have disappeared 
and only the necks remain. All that can be positively asserted regarding 
the age of these necks is that they must be later than the rocks which they 
pierce. But we may inferentially connect them with the interstratified 
lavas and tuffs by showing that they can be followed continuously outward 
from the latter as one prolonged group, having the same distribution, 
structure and composition, and that here and there they rise through the 
very highest part of the Coal-measures. It is by reasoning of this kind 
that I include, as not improbably relics of Permian volcanoes, a large number 
of vents scattered over the centre of Scotland, in the East of Fife. 
The red sandstones among which the volcanic series is intercalated cover 
several detached areas in Ayrshire and Dumfriesshire. Lithologically they 
present a close resemblance to the Penrith sandstone and breccias of Cumber- 
land, the Permian age of which is generally admitted. They lie un- 
conformably sometimes on Lower and Upper Silurian rocks, sometimes on 
the lower parts of the Carboniferous system, and sometimes on the red 
sandstones which form the highest subdivision of that system. They are 
thus not only younger than the latest Carboniferous strata, but are separated 
from them by the interval represented by the unconformability. On these 
grounds they are naturally looked upon as not older than the Permian period. 
The only palaeontological evidence yet obtained from them in Scotland is 
that furnished by the well-known footprints of Annandale, which indicate the 
existence of early forms of amphibians or reptiles during the time of the 
deposition of the red sand. The precise zoological grade of these animals, 
however, has never yet been determined, so that they furnish little help 
towards fixing the strati graphical position of the red rocks in which the 
footprints occur. 
The stratigraphical relations of the red sandstones of Ayrshire and 
Nithsdale were discussed by Murchison, Binney and Harkness. 1 These 
observers noticed certain igneous rocks near the base of the sandstones, to 
which, however, as being supposed intrusive masses, they did not attach 
importance. They regarded the volcanic tuffs of the same district as 
ordinary breccias, which they classed with those of Dumfries and Cumberland, 
though Binney noticed the resemblance of their cementing paste to that of 
volcanic tuff, and in the end was doubtful whether to regard the igneous rocks 
as intrusive or interstratified. 
In the year 1862, on visiting the sections in the Iiiver Ayr, I recognized 
the breccia as a true volcanic tuff. I furing the following years, while mapping 
the district for the Geological Survey, I established the existence of a series 
of contemporaneous lavas and tuffs at the base of the Permian basin of 
Ayrshire, and of numerous necks marking the vents from which these materials 
had been erupted. An account of these observations was published in the 
1 See Murchison’s Silwria, 4th edit. p. 331 ; Quart. Journ. Gaol. Soc. vol. vii. (1851), p. 163, 
note ; vol. xii. (1856), p. 267 ; Binney, ibid. vol. xii. (1856), p. 138 ; vol. xviii. (1862), p. 437 ; 
Harkness, ibid. vol. xii. (1856), p. 262. 
