366 Rev. Dr. Irving — On the Younger Red Rocks. 



that clear and unmistakable proof of the contemporaneity of the 

 intrusive rocks with the breccias was wanting; and it remained, 

 therefore, a somewhat moot point whether the breccias were not on 

 the whole younger than the volcanic outbursts of the district, the 

 fragments of which are abundant in the breccias. Since this meeting 

 began, however, Mr. Ussher has kindly informed me of observations 

 made by himself of the volcanic rocks overlying portions of the 

 breccia-series, which we may, therefoi'e, without much hesitation, 

 correlate with the pre-porphyritic stage of the Rothliegendes of 

 Central Germany. We may thence conclude that the very oldest 

 Permian rocks of Europe are represented in the Devon region. 



Prof. Hull has in his paper of 1892 (see Quart. Journ. Geol Soc. 

 vol. xlviii.) dwelt upon the great unconformity of the bi'eceias with 

 the Devonian Limestone, as seen in the cliifs above Babbacombe 

 Bay, where the detrital materials appear to fill an ancient (pre- 

 Permian) fjord or valley of the older Devonian land : to this I 

 should like to add an instance of unconformity, exhibited in a very 

 fine section at Saltern Cove, near Paignton, where the breccias 

 with intervening bands of coarse sandstone are seen resting nearly 

 horizontally upon the planed-olf edges of the stratified slates and 

 grits of Lower Devonian age. We have, therefore, in the neighbour- 

 hood of Torquay clear evidence of even a greater break in the 

 stratigraphical sequence between the lowest portion of the Permian 

 and the older rocks than that which exists at Zwickau and other 

 places in that part of Saxony between the unconformable Coal- 

 measures and Naumann's " pre-porphyritic stage " of the Roth- 

 liegendes ; or that which exists (as seen in the Kimberley section) 

 between the unconformable Upper Perinians (Magnesian Limestone 

 and Marl Slate) and the highly inclined Coal-measures. 



Subjoined are two section-diagrams illustrating this unconformity 

 in the Devon and Notts areas : — 



The frank recognition of the presence of a system of rocks of 

 Permian age in Devonshire by Sir A. Geikie in his Presidential 

 Address to the Geological Society of London in 1892, and the 

 re-mapping of the Devon Eed Rocks (nearly according to the 

 boundary-lines indicated in my two later papers) on the new edition 

 of the one-inch Map of the Geological Sarvey, which is exhibited 

 at this meeting of the British Association, is a result, not only 

 gratifying to myself, but one on which I think we may congratulate 

 the Director-General and his colleagues. The older mapping of the 

 Devon area by De la Beche is now officially superseded by the 

 introduction of the Devon Permians {cf. the writer's remarks, in 

 Q.J.G.S. vol. xlix. p. 83). 



Physical History of the Series. 



I have written so much in my various papers on the physical 

 relations of these rocks to one another, and to the older formations, 

 that it would be out of place on the present occasion to do much 

 more than refer to those papers. 



The land-shore- and bay-origin of the great detrital Permian 



