TRANSACTIONS OF THE SECTIONS. 49 



and wide-spread revolution have, it seems to me, nothing beyond assertion to help 

 them, foimded on that kind of wonder and awe that arises from the contemplation 

 of crags, peaks, and the inversions of the strata of great mountain-chains, or of other 

 and kindred phenomena ; while the advocates of peaceful change have little to say- 

 beyond an appeal to observed facts, gathered from a study of rocky masses and 

 their contents, which to them seem to point througliout to gradual and continuous 

 changes ; and these imperfectly understood phenomena have induced a half intuitive 

 and growing belief that the laws, both physical and biological, that govern the 

 world are quiet, progressive, and imviolent. 



Proceeding now a point fui-ther, the connexion of life with the modifications 

 which have taken place in the crust of the earth somewhat helps us in our endea- 

 vours to understand the question. As every one knows, there have been great 

 numbers of different genera and species inhabiting the world at different geological 

 epochs, the remains of which lie Duried in the various formations ; and looked at 

 on a large scale, and over broad areas, it is evident that there has been a succession 

 of life, each of the greater series of formations being more or less marked by its own 

 particular fauna. This fact led to the old geological doctrine that there had been 

 many sudden creations, by which the world was at various times peopled ; that 

 these inhabitants, after long intervals, were as suddenly destroyed ; that new crea- 

 tions came in, and that each formation was in this way marked by its peculiar forms 

 of life. When, however, it was found that in some formations a few, or sometimes 

 many, of the same species were common to two or more formations, this theory of 

 complete and sudden extinction and creation was seen to be untenable. By and 

 by, when the geological structure of Britain began to be minutely analyzed, it was 

 found in cases of unconformable stratification, even when the upper formation was 

 ill time the next hnomi member of the series to tliat which lay below, that breaks 

 in the succession of marine life, partial or total, always accompanied such uncon- 

 formities in stratification. It has, indeed, been a question with some geologists 

 whether two marine faunas, commonly recognized as belonging to two distinct and 

 far apart geological epochs, such as the Silurian and Carboniferous, could not have 

 been contemporaneous in past eras, or indeed even now. It is very possible that 

 something of this kind may have been the case ; but in my opinion only in a mixed 

 and minor way between periods or formations that in a geological sense were not 

 far apart in time. When we consider the greater formations, such as Silmian and 

 Carboniferous, Oolitic and Cretaceous, the probabilities, as I have elsewhere argued, 

 are almost infinitely against this assumption ; for if so, an Oolitic fauna, for example, 

 in whole or in part might both underlie and overlie Cretaceous formations. But, 

 however we may look upon this question, it is certain that the great principle of a 

 succession of life, showing a method of change and progress, the old disappearing, 

 and the new coming in, and breaks in succession of life, as I have shown in detail 

 elsewhere, have a close connexion with uuconformability of strata and ffajis in 

 geological time unrepresented by stratijied formations over areas of varying size, such 

 areas being determined by those agents that produced upheaval and denudation of 

 continents and islands. 



I could follow out this view with particidars, but without now doing so, this 

 reasoning seems to assure us that there never has been universally over the world 

 any complete destruction of life, but that the succession of being has gone on in 

 regidar order and sequence, though for a time, or for ever, we have lost many of the 

 records — whole chapters, whole books, in consequence of the disturbances and slow 

 denudations which the earth's crust has undergone. This must show, therefore, 

 that there never has been any universal cjitastrophe which destroyed the life of the 

 world ; especially because many of the forms are stiU alive that belong to compara- 

 tively old epochs ; and to my mind the continuity of genera and even of broader 

 distinctions leads to a like result. But great changes in physical geography have 

 often taken place in times too limited to have involved total changes of life ; for 

 life, I believe, dies out or changes not by violence or sudden edict, but by the slow 

 effects of time. The north of Europe and America has been more than half sub- 

 merged during the last glacial epoch, and re-arisen without the disappearance of 

 an)' one marine niollusk. Of the fossils of the Crag, part of an old German ocean, 



1866. 4 



