306 Mr. A. J. Jukes-Browne on the 



chalk and the appearances presented by them under the suc- 

 cessive disclosures caused by the wasting of the cliffs ; but 

 notwithstanding the attention they have attracted, the question 

 of how they came to occupy their present position has always 

 remained a moot point. 



It was also well known that the Trimmingham chalk con- 

 tained peculiar nodules of flint ; but these had never been care- 

 fully examined until the locality was visited by Mr. W. J. 

 Sollas and myself in 1875, when, finding that the hollow 

 flints disclosed very distinct traces of sponge-structure, my 

 friend undertook the study and description of these remains. 

 As the results of his examination are likely to excite further 

 interest in the chalk which contains these curious nodules, I 

 am led to offer a brief review of the known facts and opinions 

 regarding the Trimmingham bluffs ; and the present paper 

 may form a kind of introduction to Mr. Sollas's descriptions, 

 which will shortly appear in the pages of this magazine. 



The earliest notice of the Trimmingham Chalk is from the 

 pen of Mr. K. C. Taylor in 1823 * ; and some passages of this 

 are worth quoting. He says, " The most easterly point at 

 which chalk has been traced is on the coast between Mun- 

 desley and Cromer, where we find two detached masses of 

 soft chalk, with numerous layers of flint, forming insulated 

 cliffs of chalk. Several circumstances lead me to consider 

 these masses as the remnants of a stratum which once ex- 

 tended further to the north-east, in the space now occupied by 

 the sea, constituting a higher part of the series than the chalk 

 of Norwich .... These masses are continuous with a solid 

 bed of chalk, discernible at low water, reaching nearly a mile 

 in length from Trimmingham to Sidestrand, and forming a 

 level platform extending into the sea That which par- 

 ticularly distinguishes this stratum is the vast abundance of 

 a small curved oyster called Ostrea canaltculata'f. Almost 

 every part of the chalk is crowded with these shells ; and many 

 of the flints have from twenty to thirty of them adhering, 

 which, in that case, being hardened by the silex, afford the 

 best specimens." 



It will be observed that Mr. Taylor notices only two chalk 

 bluffs ;" and in Woodward's ' Geology of Norfolk ' (1833) the 

 chalk is mentioned as occurring in " two isolated disrupted 

 masses." But in the section accompanying this book three 

 separate masses are shown ; and Sir Charles Lyell, whose first 

 observations were apparently made in 1829 J, also mentions 



* Trans. Geol. Soc. ser. 2, vol. i. p. 375. 



t This is not the O. canaliculate/, of Sowerby. Dr. Barrois has lately 

 identified it with the O. lunata of Goldfuss. 



\ l Principles of Geology,' 4th edit. (1835), vol. iv. p. 90. 



