﻿476 Corres2Jondence — Rev. T. G. Bonney. 



THE CORAL RAG OF UPWARE. 

 Sir, — In Messrs. Blake and Hudleston's admirable paper on the 

 Corallian Eoclcs in England, " the well-known though very inacces- 

 sible exposure of Corallian beds at Upware " does not appear to 

 have received from the authors such careful study as those in other 

 localities. They state that in the northern quarry the beds " dip to 

 the south, or in an opposite direction to those of the Rag-pit, so that 

 there is a synclinal in which are found the Neocomian sands," and 

 they give a " presumed section," in which the said sands are repre- 

 sented as so situated. Now this section is not confirmed by any 

 evidence known to me. The dip in the northern pit — so far as 

 there is any dip at all — is northward, not southward, probably a 

 little west of north. I verified this a few days since in the company 

 of three friends, all fairly accustomed to geological observation. 

 Further, any one who has watched the working of the ' coprolite ' 

 pits, knows that the Neocomian beds rest unconformably on the 

 Coral Eag, and thin out against the side of the ridge. The road 

 along its crest (if one may use the word), between the two pits, 

 nowhere crosses Neocomian beds. Two small shallow pits have 

 indeed been opened adjoining the road on the west side, a little less 

 than a quarter and half a mile respectively south of the northern pit. 

 These seemed to be still in the same rock as it ; and thus in all 

 respects are unfavourable to the theory of a synclinal. The position 

 of the strata was given some years since by Mr. Keeping in this 

 Magazine (Vol. V. p. 272), and I have since examined several 

 sections confirming this one, with the exception that I have never 

 myself seen the Kimmeridge Clay exposed. Again, at the present time 

 there is a considerable patch of the base of the Gault laid bare, just 

 west of the south end of the Eag-pit, and perhaps four yards below 

 the crest of the limestone ; that is, exactly where it should not be on 

 any theory of a synclinal. The stratigraphy is puzzling enough ; 

 but, so far as the evidence goes, it appears to me rather in favour of 

 the old theory of an anticlinal as represented by Fitton (Trans. Geol. 

 Soc, vol. iv. pi. xi.). The present authors may be right in assign- 

 ing to the rock of the northern pit a lower horizon than that of the 

 southern ; but I have no hesitation in saying that the evidence at 

 present is only palEeontological, and this is not strong. 



The other matter is a personal one, and refers to their mention of 

 my own account of this district. I am well aware that in my 

 Geology of Cambridgeshire it was " partially, but not very fully, 

 described," because the book only professes to be a sketch for the 

 use of students. At the same time, when authors call attention to 

 an imperfection, one may fairly expect that they will considerably 

 augment our stock of knowledge. I venture to assert that the 

 questionable statement discussed above is the only material addition 

 contained in the paper on the Corallian rocks. The two accounts 

 are about equal in length, and contain as nearly as possible the same 

 facts. Again, the authors' statement about the position which I 



