I 

 THE AGE OF THE EAETH 



THE close of one century, the dawn of another, may 

 naturally suggest some brief retrospective glance 

 over the path along which our science has advanced, and 

 some general survey of its present position from which 

 we may gather hope of its future progress ; but other con- 

 nexion with geology the beginnings and endings of 

 centuries have none. The great periods of movement 

 have hitherto begun, as it were, in the early twilight 

 hours, long before the dawn. Thus the first step forward, 

 since which there had been no retreat, was taken by 

 Steno in the }^ear 1669 ; more than a century elapsed 

 before James Hutton (1785) gave fresh energy and better 

 direction to the faltering steps of the young science ; while 

 it was less than a century later (1863) when Lord Kelvin 

 brought to its aid the powers of the higher mathematics 

 and instructed it in the teachings of modern physics. 

 From Steno onward the spirit of geology was catas- 

 trophic ; from Hutton onward it grew increasingly 

 uniformitarian ; from the time of Darwin and Kelvin it- 

 has become evolutional. The ambiguity of the word 

 " uniformitarian " has led to a good deal of fruitless 

 logomachy, against which it may be as well at once to 

 guard by indicating the sense in which it is used here. 



2 i 



