262 ON THE ORIGIN OF SPECIES 



preserve the remains before they had time to decay. 

 On the other hand, as long as the bed of the sea re- 

 mained stationary, thick deposits could not have been 

 accumulated in the shallow parts, which are the most 

 favourable to life. Still less could this have happened 

 during- the alternate periods of elevation ; or, to speak 

 more accurately, the beds which were then accumulated 

 will have been destroyed by being- upraised and brought 

 within the limits of the coast-action. 



Thus the geological record will almost necessarily be 

 rendered intermittent. I feel much confidence in the 

 truth of these views, for they are in strict accordance 

 with the general principles inculcated by Sir C. Lyell ; 

 and E. Forbes subsequently but independently arrived 

 at a similar conclusion. 



One remark is here worth a passing notice. During 

 periods of elevation the area of the land and of the 

 adjoining shoal parts of the sea will be increased, and 

 new stations will often be formed ; — all circumstances 

 most favourable, as previously explained, for the forma- 

 tion of new varieties and species ; but during such 

 periods there will generally be a blank in the geological 

 record. On the other hand, during subsidence, the 

 inhabited area and number of inhabitants will decrease 

 (excepting the productions on the shores of a continent 

 when first broken up into an archipelago), and conse- 

 quently during subsidence, though there will be much 

 extinction, fewer new varieties or species will be formed ; 

 and it is during these very periods of subsidence, that 

 our great deposits rich in fossils have been accumulated. 

 Nature may almost be said to have guarded against 

 the frequent discovery of her transitional or linking 

 forms. 



From the foregoing considerations it cannot be 

 doubted that the geological record, viewed as a whole, 

 is extremely imperfect ; but if we confine our attention 

 to any one formation, it becomes more difficult to 

 understand, why we do not therein find closely 

 graduated varieties between the allied species which 

 lived at its commencement and at its close. Some 



