168 Dr. Alexander Irving — The Trias of Devonshire. 



I have never described (I believe) tbe breccias as ' doloinitic,' and 

 (2) I am not aware that I ever spoke of them as ' conglomerates ' ; 

 on the contrary, I took particular pains in recording my close 

 observations of the breccia at the Otter mouth (A, p. 153) to show- 

 that it could not be called a conglomerate, on account of the extreme 

 paucity of rounded included fragments. Further, I had no evidence 

 of the presence of magnesium carbonate in the rock, without which 

 the term ' dolomitic ' would not be justified. 



We come now to the main point. Mr. Somervail goes on to say : 

 " This description certainly does not apply to the alleged breccias on 

 the left bank of the Sid," emphasizing by italics this categorical 

 denial. This requires severe examination. 



Mr. Somervail's caricature of my description of the breccias 

 (supra) does not apply with scientific precision to either of them at 

 the mouth of the Sid or the mouth of the Otter ; but my description 

 applies to them at both places, although at the Sid there is just this 

 difference, that the breccia is not so massively developed, and is not 

 quite so strongly calcareous, owing probably to the fact that the 

 carbonate of lime has been partly leached out from the matrix by 

 longer exposure. I have, as I write, lying betbre me six specimens 

 of the breccias in question,^ which were labelled at the time when my 

 work in Devon was done, and have only lately been again brought 

 to light. Four of these are labelled " Basal Breccia of the Keuper, 

 left bank of the Otter," and on two of these is written the reference 

 "Q.J.G-.S., voL xliv, 153" (paper A) ; the fifth is labelled "basal 

 breccia of the Keuper at Harpford " ; and the sixth is labelled 

 " Calcareous breccia, base of the Keuper, mouth of the Sid." Of 

 these specimens, as judged by the rough test of the same dilute acid, 

 the one from Harpford and two of those from the Otter mouth ai'e 

 very strongly calcareous (one, indeed, to such an extent that the 

 matrix is in places macrocrystalline) ; the specimen from the mouth 

 of the Sid effervesces rather less strongly with the acid than those, 

 but more strongly certainly than the remaining two specimens from 

 the Otter mouth. Again, a comparison of them reveals the fact that 

 while the breccia-structure of the specimen from Harpford and of 

 two of those from the Otter is more conspicuous than in that from 

 the Sid (owing to the larger size of the contained fragments), in the 

 remaining two from the Otter that is not the case. I need not 

 repeat here what I wrote some fifteen years ago as to my hesitation 

 to fix upon the Sid breccia as the base of the Keuper at that spot, 

 until confirmed in that view by so experienced an observer as 

 Professor Hull, who brought to the subject his trained experience 

 of more than twenty years' work in the Eed Rock Series of the 

 Midlands and the Severn country. But I may add that, in my 

 annotated copy of paper A, I find the following marginal note, 

 made at the time of my visit with Hull : — " There is a more definite 

 breccia (true base of the Keuper) forming the shelf of rock, on 

 w^hich the ladder rests at the eastern end of the foot-bridge across 



^ These were exhibited at the meetings of the Geological Society when my papers 

 were read. 



