Origin of Species Variorum

Comparison with 1869

CHAPTER IX.

ON THE IMPERFECTION OF THE GEOLOGICAL RECORD.

On the absence of intermediate varieties at the present day— On the nature of extinct intermediate varieties; on their number— On the .. lapse of time, as inferred from the rate of denudation and of deposition— On the lapse of time as estimated by years— On the poorness of our palæontological collections— On the denudation of granitic areas— On the intermittence of geological formations— On the absence of intermediate varieties in any one formation— On the sudden appearance in the lowest known fossiliferous strata— Antiquity of the habitable earth.

IN the sixth chapter I enumerated the chief objections which might be justly urged against the views maintained in this volume. 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 difficulty. I assigned reasons why such links do not commonly occur at the present day, under the circumstances apparently most favourable for their presence, namely on an extensive and continuous area with graduated physical conditions. I endeavoured to show, that the life of each species depends in a more important manner on the presence of other already defined 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 endeavoured, 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

CHAPTER IX.

ON THE IMPERFECTION OF THE GEOLOGICAL RECORD.

On the absence of intermediate varieties at the present day— On the nature of extinct intermediate varieties; on their number— On the vase lapse of time, as inferred from the rate of deposition and of denudation— On the poorness of our palæontological collections— On the denudation of granitic areas— On the intermittence of geological 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.