o6 
THE PERMIAN VOLCANOES 
BOOK VII 
younger formation, they should not be found penetrating it. 1 It seems 
almost certain that they must he of an age intermediate between the Coal- 
measures of South Staffordshire and the surrounding breccias and sandstones 
of the 1 ermian series. And as there is clear evidence of contemporaneous 
volcanic action in the lowest part of the Permian system to the north in 
Scotland and to the south in Devonshire, the inference seems not unreason- 
able that these intrusive basalts of the Midlands are most probably of 
Permian age. 
No trace of vents has been met with in the Coal-measures of the Mid- 
land district or among the surrounding older rocks, nor any proof that the 
abundant sills and veins were connected with the eruption of volcanic 
materials at the surface. Nevertheless, from the analogy of the structure 
of these intrusive sheets to that of the sills in such volcanic districts as the 
southern half of Scotland, we may well believe that they were connected 
here and there with eruptive vents, and thus that besides the northern and 
southern districts of Permian volcanoes, there rose a central group among 
the lagoons of the heart of England. Though no vestige of any such 
group has been detected, we must remember that a large portion of the 
Midlands is overspread with Permian and Triassic deposits, and that 
much more igneous rock may be concealed than appears at the surface. 
Possibly there may be buried under these younger sheets of red sandstone 
and marl, lavas and tuffs with their connected vents, such as may be seen 
where the Permian volcanic series has been laid bare by denudation in 
Ayrshire and Devonshire. In this respect it would be interesting to make 
a thorough examination of the Permian breccias of the district, with the 
view of discovering whether, though the volcanic rocks in situ may still lie 
covered up, fragments of them may not be found in these deposits. 
1 Only one instance is known where in Staffordshire any igneous rock has heen intruded into 
rocks younger than the Coal-measures (Allport, Quart. Journ. Geo/. Soc. vol. xxx. p. 551 ; Sheet 
72 S.W. of the Geological Survey, and Horizontal Sections, Sheet 57). It forms a dykewhichlias 
been traced near Norton Bridge, Swinnerton and Butterton, running for 8 miles in a N.N.W. 
direction, and rising through Permian, Bunter and Keuper strata. It is a highly basic olivine- 
basalt, and is unquestionably a dyke. -Mr. ,T. Kirkby, who has recently mapped and described it 
('Trans. North Staffordshire Naturalists’ Meld-Chib, xxviii. (1894), p. 129), suggests that it may be 
connected witli the igneous rocks of the South Staffordshire coal-field. But of this idea there is no 
evidence. The last point to which the dyke has been traced is some five-and-twenty miles from 
the nearest known portion of the dolerites of the coal-field, I have little doubt that this dyke is 
really an outlying member of the great system of Tertiary dykes described in Book. VIII. of the 
present work. 
