Presidential Address—The Geology of Devon. 507 
Irving, who has paid some attention to these questions, differs from 
Mr. Ussher, and still more from Mr. Pengelly, in the belief that the 
breccia series is of Permian age. He regards it, in fact, as the 
result of terrestrial and littoral deposits on the flanks and on the shore- 
line of the old mountain region of which the Devon-Cornwall 
peninsula is one of the remnants, the high inclination of the dip 
being in favour of its being mainly composed of mountain detritus. 
It would be difficult indeed to assign any other origin to the 
wonderful group of beds which constitute the sea-cliff between 
Teignmouth and Dawlish. The only matter in dispute is the precise 
chronology of these beds. Shall we say with Mr. Pengelly that 
they are of Keuper age? or with Mr. Ussher and Mr. Ormerod, 
that they are of Bunter age? or shall we agree with Mr. Irving that 
they are of Permian age? In the absence of marine mollusca 
the precise age of any series of beds is difficult to determine; all 
that we can affirm with absolute certainty is that they belong to the 
Permio-Triassic interval, and that in this country such beds are 
more usually Permian than Triassic. The brecciated beds of the 
Leicestershire Permians, for instance, have been recently shown to 
be composed of the re-arranged talus of the harder portions of the 
Palzeozoic rocks surrounding that part of the old Permian lake. 
Tur Post-CarsonireRous INTERVAL. 
Leaving the question of the actual chronology of the Dawlish 
beds as almost hopeless in our present state of knowledge, we must 
be content to bear in mind the main facts of the case, viz. that 
towards the close of the Carboniferous period one of those great 
shifts in the earth’s crust occurred, of which there have been three 
or four during geological time. Roughly speaking the Paleozoic 
epoch terminated with this great movement, whose flexing action 
has, in the main, governed the axes of the series of synclinals and 
anticlinals existing between the Bristol and English Channels, with 
an extension towards the south so as to include the peninsula of 
Brittany. The principal of these earth-throes occurred during the 
unrepresented period of time which intervened between the Coal- 
measures, as usually developed, and the Permian; and though there 
are evidences of subsequent oscillation in our district to a moderate 
extent, no instances of folding and contortion occur in the beds 
deposited afterwards. Then it was that the building of the British 
Isles commenced in earnest, and that the first rude sculpturings of 
the future Devonshire were made. Some of these points we shall 
have to consider again in reference to the general structure of the 
county. 
Tur CaRBONIFEROUS. 
Before proceeding to answer the remainder of Mr. Pengelly’s 
questions, a few words may be devoted to a formation which in 
Devonshire is both extensive and disappointing. No attempt will 
be made to correlate any portions of these beds wih their pre- 
sumed equivalents on the Welsh side. All we can say is, that 
