of the White Chalk. 335 



ing error has been only averted by the acuteness of a practised 

 and able palaeontologist. In immediate connexion with the chalk 

 beds I will name one other instance which is at the present time 

 drawing forth frequent expressions of interest and surprise from 

 geologists, — I mean the alleged discovery of a bed of Ammonites 

 and allied forms in the upper part of the chalk ; — a discovery 

 which, without expressing a positive opinion as to the absolute 

 fact implied in it, I can safely say is at present un sustained by 

 any facts in my own collection (in which is a large series of the 

 specimens) or in any other which I have seen, and I shall pre- 

 sently show why the allegation (which implies an induction) has, 

 at present, no necessary basis of absolute fact, even admitting the 

 alleged localities to be correctly stated. 



That the interest and importance of geology as a science, in 

 all its branches and applications, mainly depend upon that 

 stratigraphical exactness on which I have before insisted*, must 

 be admitted equally by the palaeontologist, the engineer and the 

 surveyor. I propose therefore, very briefly, to call attention now 

 to some points : — I. As to the different and differing beds of the 

 white chalk, by which I mean, that which lies above the chalk 

 marl : and II. As to the causes of the frequent confusion which 

 exists in the determination of the true position of chalk fossils ; — 

 which will lead us directly to another interesting question, namely 

 the faults and dislocations which have taken place in the chalk 

 itself, and the time or times at which these have taken place. 



I. There is so much external resemblance between hand spe- 

 cimens of the chalk from any of the beds above included, that it 

 is little surprising if those not familiar with actual sections gene- 

 ralize the whole together. 



Dr. Mantell divides the beds of which I am speaking into 

 " upper or flinty chalk n and " lower chalk." This division, which 

 was made in his ' South Downs' (pp. 79 & 139), is retained in his 

 'Medals of Creation ' (p. 33). The same division is made by 

 Mr. Lyell (under different names) in his ' Elements/ vol. i. p. 386 

 (ed. 1841), and, though with even less distinctness, in vol. ii. 

 p. 180. Mr. Morris, in his * Catalogue' (p. ix), makes a similar 

 division, and in Mr. Tennant's ' Stratigraphical List ' just pub- 

 lished by the " Society for Promoting Christian Knowledge " a 

 like division is made (p. 37). 



In all these cases the presence or absence of flints is made the 

 ground of division of the beds. I do not deny that in one part 

 of the white chalk flints are common, in another part absent or 

 rare. But I altogether demur to this being assumed as any basis 

 for a natural division, believing that presence or absence to be, 



* In loc. cit. 



