468 Mr. Charlesworth's Reply to Mr. Woodward's 



Had the various species of Terebratula and other chalk 

 fossils, which are of such frequent occurrence in the crag of 

 Norfolk, been derived from a tertiary instead of a secondary 

 formation, their extraneous origin would not have been de- 

 tected, and they would have been regarded as among those 

 shells which are common to different tertiary periods. In de- 

 termining the age of the Norfolk crag according to the prin- 

 ciples laid down by Mr. Lyell, these shells would have swelled 

 the list of extinct species, and the important fallacy which 

 must thence have arisen is too obvious to require pointing 

 out. I shall shortly make public some observations on the 

 subject of fossils belonging to different periods being occa- 

 sionally associated in the same deposit. I have strong evi- 

 dence to show, that, in the same way as in Norfolk second- 

 ary fossils have been introduced into the overlying tertiary 

 beds, — in the same way as in Suffolk I believe the Testacea of 

 the coralline crag to have been removed into the superincum- 

 bent deposit, — so also are the formations now in progress along 

 some parts of our eastern coast deriving no inconsiderable 

 proportion of their organic contents from the destruction of 

 strata which are supposed to represent the organization of the 

 older pliocene period. If we may look forward to the time 

 when these deposits shall have become the subject of geologi- 

 cal inquiry, and suppose that their age is to be determined by 

 comparing such fossil shells as may be obtained from them 

 with the then existing species, how evidently inaccurate will 

 be the conclusions formed from such an examination ! By 

 the time that the deposits now in progress become accessible, 

 every vestige of the crag will probably have disappeared. 

 Hence there will be nothing to excite the slightest suspicion 

 that they contain the organic products of different periods, 

 any more than there would have been in the instance of the 

 red crag had the coralline been entirely destroyed *. 



* These observations have no reference to the principles which Mr. 

 Lyell has advocated in determining the age of tertiary deposits: they apply 

 exclusively to the errors that may arise in the application of those princi- 

 ples. The bed of the German Ocean, between Scarborough and Heme 

 Bay, is strewed with the bones of extinct Mammalia, in prodigious num- 

 bers, and to which abundance of living Balani, with other Testacea, are 

 adherent. There is, perhaps, no limit to the complication of errors which 

 have arisen from its being universally considered that the association of 

 different organic remains in a regularly stratified deposit necessarily implied 

 their co-existence. In illustration of this I would refer to a paper by the 

 Rev. Mr. Vernon (now Vernon Harcourt) in the Philosophical Magazine 

 for September 1829 (Phil. Mag. and Annals, N. S. vol. vi. p. 225 et seq.) 

 on the discovery of extinct Mammalia in a deposit with recent species of 

 Testacea at North Cliff. See also Mr. Lyell's observations on the same 

 subject, in his " Principles of Geology." 



