Uniformitarianism 8i 



on]}7 possible on the theory that unusual and gigantic 

 displays of force had caused them. On the other hand, 

 Hutton and Lyell attempted to find adequate explana- 

 tion of the greatest changes in the slow forces which 

 may be seen in operation at the present time. Slow 

 movements of upheaval and depression, amounting at 

 most to an inch or two in a century, may be shown to be 

 actually in existence now, and such slow changes acting 

 for very many centuries would account for the raising 

 of continents above the sea, so that old sea-bottoms be- 

 came the surface of the land, and for the depression 

 of land areas so that new sedimentary rocks might be 

 deposited upon them. They shewed how air and water 

 slowly crumbled away the hardest rocks, and how 

 rivers deepened their beds steadily but excessively 

 slowly ; and they held that while great catastrophic 

 changes might occasionally have occurred, there was 

 ample evidence of the present operation of forces which, 

 granted sufficient time for their operation, would have 

 made the crust of the earth such as it is. This doctrine 

 of Uniformitarianism, of the action of similar forces in 

 the past and present history of the earth, had almost 

 completely triumphed over the older catastrophic views. 

 As Huxley put it, the school of catastrophe put no 

 limit to the violence of forces which had operated ; the 

 uniformitarians put no limit to the length of time 

 during which forces had operated. 



" Catastropliism has insisted upon the existence of a practi- 

 cally unlimited bank of force, on which Ihe theorist might 

 draw ; and it has cherished the idea of development of the 

 earth from a state in which its form, and the forces which it 

 exerted, were very different from those which we now know. 



" Uniformitarianism, on the other hand, has with equal justice 



insisted upon a practically unlimited bank of time, ready to 

 6 



