68 KEY. A. IRVING ON THE EED KOCKS 



6. Supplementary Note to the Paper on tlie ' Bed E,ocks of the 

 Devon Coast-section' (Q. J. G. S. 1888). By the Rev. A. 

 Irying, D.Sc, B.A., F.G.S. (Bead ]S"ovember 25, 1891.) 



Contents. 



Page 



I. The base of the Keuper in Devon 68 



TI, The Permian Age of the 'Lower Red Sandstones' of Devon 72 



III. The Age of the Breccias , 75 



I. The Base oe the Keuper in Devon. 



In my former paper I took for the basement-limit of the Keuper 

 what v^^e might fairly call the base of the ' building-stones.' 

 Prof. Hull, on a visit with me to Sidmouth in the summer of 1891^ 

 suggested that the bed of breccia below the footbridge over the Sid 

 would make a better basement-line for the Keuper formation, and 

 bring the classification more into harmony with the lines of demar- 

 cation adopted by himself and others for the Midlands and else- 

 where. Though I had noted this bed and referred to it in my 

 paper, its character as a distinct basement-breccia had not im- 

 pressed itself upon me, since 1 regarded it as nothing more than one 

 of the intercalated lenticular masses of the Bunter Sandstone. 



A closer examination reveals, however, its true character. It con- 

 tains angular and subangular fragments of grit and quartz, enclosed 

 in a dull brick-red matrix. What mainly deterred me from adopting 

 this breccia as a basal line for the Keuper was the very marked 

 current-bedded structure of the 10 to 15 ft. of coarse Bunter-like 

 sandstone, which follows the breccia in the upward succession on 

 the face of the cliff. This, however, is not a real difiiculty, because — 

 as Prof. Hull pointed out to me on the ground — this structural 

 character is not at all uncommon in the basement-beds of the 

 Keuper below the Waterstones in other areas. On looking into the 

 literature of the subject a little more closely since my visit to 

 Devon with Prof. Hull, I find that the description of the Prodsham 

 Beds of Cheshire by Mr. Strahan ^ applies so exactly to the beds 

 above the breccia on the east of Sidmouth that it is impossible to 

 feel any further hesitation in accepting them, together with the 

 breccia, as the true Keuper basement-beds in Devon as in Cheshire. 



Whether the breccia-line is continued to the west of Sidmouth at 

 the foot of the High Peake cliffs ^ I am not able to say positively,, 

 until I have an opportunity of more closely examining the cliffy 

 there with special reference to this point. There is, however, no 

 reason in the nature of things why the breccia should be con- 

 tinuous, but rather the reverse. The absence of it would certainly 



1 Geol. Mag. for 1881 , pp. 396 et seg. * On the Lower Sandstone of Cheshire/ 

 by A. Strahan, M.A., F.G.S. 



^ In Quart. Journ. Geol. Soc. vol. xxxii. (1876) p. 283, Mr. Ussher men' 

 tions a ' conglomerate bed . . . which crops out below High Peake Hill.' 



