VI 



Geological Time 1 



Among the many questions of great theoretical import- 

 ance which have engaged the attention of geologists, 

 none has in late years awakened more interest or 

 aroused livelier controversy than that which deals with 

 Time as an element in geological history. The various 

 schools which have successively arisen — Cataclysmal, 

 Uniformitarian, and Evolutionist — have had each its 

 own views as to the duration of their chronology, as 

 well as to the operations of terrestrial energy. But 

 though holding different opinions, they did not make 

 these differences matter of special controversy among 

 themselves. About thirty years ago, however, they 

 were startled by a bold irruption into their camp from 

 the side of physics. They were then called on to 

 reform their ways, which were declared to be flatly 

 opposed to the teachings of natural philosophy. Since 

 that period the discussion then started regarding the 

 age of the Earth and the value of geological time has 



1 Presidential Address to the Geological Section of the British 

 Association for the Advancement of Science at the Dover Meeting 

 1899. 



