Vol. 56.] MR. F. W. HAEMER OX THE CRAG OP ESSEX. 705 



The Pliocene Deposits of the East of England. — Part II : The 

 Crag of Essex (Waltonian) and its Relation to that of Suffolk 

 and Norfolk. By E. W. Harmee, Esq., E.G.S. With a Report 

 on the Inorganic Constituents of the Crag. By Joseph Lomas, 

 Esq., E.G.S. (Read May 9th, 1900.) 



Contents. 



Page 



I. Introductory 705 



II. The Crag of Essex— Waltonian 709 



III. The Eelation of the Waltonian Beds to other Horizons of 



the Red Crag and to the Norwich Crag 719 



IV. The Derivative Mollusca of the Red Crag 726 



V. The Probable Conditions under which the Red Crag Deposits 



Originated 



VI. Summary 735 



VII. Appendix 738 



I. Introductory. 



Searles V. Wood, as is well known, regarded the shell-bed of 

 Walton-on-the-Naze, with its strongly-marked southern fauna, as 

 older than any other part of the Red Crag, grouping the rest of that 

 formation, in which northern shells occur more or less abundantly, 

 under the name of the Crag of Sutton and B u tie y, 1 although 

 he believed that of the latter locality to be the newer of the two. 2 

 Prestwich, on the other hand, maintained that all the Red Crag 

 beds, and to some extent the Norwich Crag also, were contem- 

 poraneous 3 ; and this view is, I believe, still held by no less an 

 authority than the ex-President of the Geological Society. 4 In the 

 face of such a difference of opinion, it seemed to me necessary to 

 return to the subject, in order that, if possible, some more definite 

 conclusions might be arrived at. In the hope therefore of obtaining 

 further evidence as to the correct classification of these beds, I have 

 spent my leisure time during the past five or six years in revisiting 

 every part of the Crag district, and in the examination of all the 

 more important collections of Crag fossils. 



The view that the Red Crag deposits are all of the same age 

 appears, at first sight, not unreasonable, though it is not so easy to 

 understand why those of the Norwich Crag should have been 

 grouped with them. As to the former, many, perhaps most, of 

 their more characteristic mollusca are found in every part of the 

 formation, so that lists of fossils from different localities present a 

 striking resemblance to each other. 



1 ' Suppl. Crag Moll.' Monogr. Pal. Soc. (1872-74) p. 203, & elsewhere. S. V. 

 Wood, Jun. and I expressed a similar opinion in the same work, p. vii. At that 

 time we did not see our way satisfactorily to separate the Sutton and Butley 

 deposits. 2 Quart. Journ. Geol. Soc. vol. xxii (1866) p. 538. 



3 Ibid. vol. xxvii (1871) p. 325. Prestwich believed, however, that in many 

 of the Red Crag exposures an upper division could be traced, but he did not 

 attempt to show that it contained mollusca different from those of the under- 

 lying beds. 



• 4 Proc. Geol. Assoc, vol. xv (1898) p. 443. 

 Q. J. G. S. No. 224. 3 b 



