540 On Mr. LyelVs Classification 



really producing such an effect as the one just described, 

 admits of almost actual demonstration ; for the fossil shells of 

 the crag are thrown up along various parts of the Suffolk 

 coast, several miles from the spots in which they have been 

 carried down. 



" It may be said that these older shells, entering into the 

 new deposits, carry with them evidence of the stratum from 

 which they have been derived ; or that, at all events, their 

 worn appearance would distinguish them from the more recent 

 Mollusca with which they are associated. This is so far from 

 being the case, that considerably finer and more perfect speci- 

 mens of the Voluta Lambert/ can be picked up on the sea shore, 

 where they have been dashed by the waves upon a shingly 

 beach, than can ever be obtained from the beds of the crag 

 formation itself. In fact, this gradual process of degradation 

 appears, in many instances, to be of all others the most favour- 

 able for detaching organic remains from the matrix in which 

 they are embedded ; and, with respect to the evidence that 

 might possibly be supposed to arise from a difference in litho- 

 logical character, it should be remembered, that, even if such 

 indications did exist, by the time these new deposits become 

 accessible, every vestige of the crag will have disappeared. 

 There will, consequently, be nothing to excite the slightest 

 suspicion that the crag species are not contemporaneous with 

 all the organic remains associated with them. In adopting 

 this line of argument, I am, of course, supposing that the 

 geologists of a future epoch have the same amount of inform- 

 ation respecting the history of the tertiary deposits of those 

 days that we have of our own, and not that a geological 

 record of events has been continued up to that period. 



" To a certain amount, then, this admixture of fossil with re- 

 cent shells, even in regularly stratified deposits, cannot be de- 

 nied ; but it may be urged that it takes place only under peculiar 

 circumstances, and to such a limited extent as would never 

 interfere with the accuracy of general inductions founded 

 upon extended research and careful practical observation. 



" If, however, we enlarge our field of observation, we 

 shall find that a process has been going forward, attended 

 with similar results, over a tract the superficial extent of which 

 far exceeds that occupied by the whole of the crag formation. 

 The bed of the ocean, all along the coasts of Norfolk, Suffolk, 

 and Essex, and probably as far as Kent on the one side, 

 and Yorkshire on the other, is strewed with multitudes of 

 the bones of extinct Mammalia. These remains have been 

 taken up twenty miles from the shore; and, in dredging for 

 oysters, the fishermen have suffered considerable inconvenience 



