X GEOLOGICAL REFORM 307 



enough claim these appellations, standing side by 

 side in Britain. I shall call one of them CATA- 

 STROPHISM, another UNIFORMITARIANISM, the third 

 EVOLUTIONISM ; and I shall try briefly to sketch 

 the characters of each, that you may say whether 

 the classification is, or is not, exhaustive. 



By CATASTROPHISM, I mean any form of geo- 

 logical speculation which, in order to account for 

 the phenomena of geology, supposes the operation 

 of forces different in their nature, or immeasur- 

 ably different in power, from those which we at 

 present see in action in the universe. 



The Mosaic cosmogony is, in this sense, cata- 

 strophic, because it assumes the operation of 

 extra-natural power. The doctrine of violent 

 upheavals, debacles, and cataclysms in general, is 

 catastrophic, so far as it assumes that these were 

 brought about by causes which have now no 

 parallel. There was a time when catastrophism 

 might, pre-eminently, have claimed the title of 

 " British popular geology " ; and assuredly it has 

 yet many adherents, and reckons among its sup- 

 porters some of the most honoured members of 

 this Society. 



By UNIFORMITARIANISM, I mean especially, the 

 teaching of Hutton and of Lyell. 



That great though incomplete work, "The 

 Theory of the Earth," seems to me to be one of 

 the most remarkable contributions to geology 

 which is recorded in the annals of the science. 



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