X GEOLOGICAL REFORM 307 



enough claim these appellations, standing side by 

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

 STROPHISM, another UNiFORMiTARiANlSM,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, d^hddcs, 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 gi^eat 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. 



