CHAPTER XXXII 
PERMIAN VOLCANOES OF ENGLAND 
The Devonshire Centre — Eruptive Rocks of the Midland Coal-fields. 
Iro.m the south of Scotland we need to pass to the extreme south-west of 
England before we again encounter a group of volcanic rocks which may be 
referred with some confidence to the Permian period. An interesting group 
of lavas and tuffs has been preserved in some of the valleys over a limited 
area in the east of Devonshire. The Midland coal-fields, however, are 
traversed by a series of basic eruptive rocks which are younger than the 
Coal-measures, and may possibly be Permian. Their mode of occurrence, 
and the arguments regarding their geological age, will be given in the 
present chapter. 
1. DEVONSHIRE 
The counties of Devon and Cornwall furnish one of the most striking 
examples to be met with in Britain of the persistence of volcanic action 
over a limited area through a long succession of geological periods. The 
extensive eruptions in Devonian time were followed after a long interval by 
a diminished series in the Carboniferous period. But the subterranean 
energy was not then wholly exhausted, for it showed itself on a feeble 
scale in at least one limited tract of the same region during the Permian 
period. Thus throughout the later half of Palieozoic time the extreme south- 
west of England continued to be a theatre of volcanic action. 
The geological age of the igneous rocks now to be referred to depends 
upon tire particular place in the geological record to which we assign the 
remarkable breccias and sandstones with which they are associated. By 
many geologists who have been unable to recognize any true break in the 
red rocks from their base up to the bottom of the Lias, these strata have 
been grouped as one great series referable to the “ ISTew Red Sandstone ” or 
Trias. This is the classification adopted on the one-inch maps of the 
Geological Survey. On the other hand, various able observers have pointed 
out the close resemblance of the coarse and fine breccias at the bottom of 
