2GG IMPEKFECTIO^' OF THE Chap. IX. 



CHAPTER IX. 



ON TIIK EMPKRFECTIOX OF THE GEOLOGICAIi EECOED. 



On the Absence of Intermediate Varieties at the Present Day— On the Nature of Ex- 

 tinct Intermediate Variotii's : on their Number— On the Lapse of Time, as in- 

 ferred from the Ilate of Denudation and of Deposition — On the Lapse of Time as 

 estimated V)y Years — On the Poorness of our Paleontologieal Collections — on the 

 Denudation of Granitic Areas— On the Intermittence of Geolo'jrical Formations — 

 On the Absence of Intermediate Varieties in any one Formation— On the sudden 

 Appearance of Groups of Species— On their sudden Appearance in the lowest 

 known Fossiliferous Strata — Antiquity of the Uubitablc Earth. 



In the sixth chapter I enumerated tlie chief objections 

 which iTiio;lit be justly urged against the views maintained in 

 this A-olume. Most of them have now been discussed. One, 

 namely, the distinctness of specific forms, and their not being 

 blended together by innumerable transitional links, is a very 

 obvious dilliculty. I assigned reasons why such links do not 

 commonly occur at the present day, under the circumstances 

 apparently most favorable for their presence, namely, on an 

 extensive and continuous area with graduated physical condi- 

 tions. I endeavored to show that the life of each species 

 depends in a more important manner on the presence of other 

 alrcady-deiined organic forms, than on climate ; and, therefore, 

 that the really governing conditions of life do not graduate 

 away quite insensibly like heat or moisture. I endeavored, 

 also, to show that intermediate varieties, from existing in lesser 

 numbers than the forms which they connect, will generally be 

 beaten out and exterminated during the course of further 

 modification and improvement. The main cause, however, of 

 innumerable intermediate links not now occurring everywhere 

 throughout Nature depends on the very process of natural 

 selection, through which new varieties continually take the 

 places of and exterminate their parent-forms. But just in pro- 

 portion as this process of extermination has acted on an enor- 

 mous scale, so must tlie number of intermediate varieties, 

 which have formerly existed, be truly enormotis. ^V^ly, then, 



