THE LAWS OF GEOLOGICAL ACTION. 5 



tions of life were once more established, and new races of ani- 

 mals and plants sprang into existence, to last until the super- 

 vention of another fever-fit. 



Such is the past history of the globe, as sketched for us, in 

 alternating scenes of fruitful peace and revolutionary destruc- 

 tion, by the earlier geologists. As before said, we cannot won- 

 der at the former general acceptance of Catastrophistic doc- 

 trines. Even in the light of our present widely-increased 

 knowledge, the series of geological monuments remains a broken 

 and imperfect one ; nor can we ever hope to fill up completely 

 the numerous gaps with which the geological record is defaced. 

 Catastrophism was the natural method of accounting for these 

 gaps, and, as we shall see, it possesses a basis of truth. At pres- 

 ent, however, catastrophism may be said to be nearly extinct, and 

 its place is taken by the modern doctrine of "Continuity" or 

 " Uniformity " a doctrine with which the name of Lyell must 

 ever remain imperishably associated. 



The fundamental thesis of the doctrine of Uniformity is, 

 that, in spite of all apparent violations of continuity, the se- 

 quence of geological phenomena has in reality been a regular 

 and uninterrupted one; and that the vast changes which can be 

 shown to have passed over the earth in former periods have 

 been the result of the slow and ceaseless working of the ordi- 

 nary physical forces acting with no greater intensity than they 

 do now, but acting through enormously prolonged periods. The 

 essential element in the theory of Continuity is to be found in 

 the allotment of indefinite time for the accomplishment of the 

 known series of geological changes. It is obviously the case, 

 namely, that there are two possible explanations of all phenom- 

 ena which lie so far concealed in " the dark backward and 

 abysm of time," that we can have no direct knowledge of the 

 manner in which they were produced. We may, on the one 

 hand, suppose them to be the result of some very powerful cause, 

 acting through a short period of time. That is Catastrophism. 

 Or, we may suppose them to be caused by a much weaker force 

 operating through a proportionately prolonged period. This is 

 the view of the Uniformitarians. It is a question of energy 

 versus time; and it is time which is the true element of the case. 

 An earthquake may remove a mountain in the course of a few 

 seconds; but the dropping of the gentle rain will do the same, 

 if we extend its operations over a millennium. And this is true 

 of all agencies which are now at work, or ever have been at 

 work, upon our planet. The Catastrophists, believing that the 



