THE LAWS OF GEOLOGICAL ACTION. 5 



wonder at the former general acceptance of Catastrophistic 

 doctrines. 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 

 present, however, catastrophism may be said to be nearly ex- 

 tinct, and its place is taken by the modern doctrine of " Con- 

 tinuity " 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 

 phenomena 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 Catas- 

 trophism. 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 ques- 

 tion of energy versus time ; and it is time which is the true ele- 

 ment 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 millen- 

 nium. And this is true of all agencies which are now at work, 

 or ever have been at work, upon our planet. The Catastro 

 phists, believing that the globe is but, as it were, the birth of 

 yesterday, were driven of necessity to the conclusion that its 

 history had been checkered by the intermittent action of par- 

 oxysmal and almost inconceivably potent forces. The Unifor- 

 mitarians, on the other hand, maintaining the " adequacy of 

 existing causes," and denying that the known physical forces 

 ever acted in past time with greater intensity than they do at 

 present, are, equally of necessity, driven to the conclusion that 



