IN THE LAST HALF- CENTURY. 139 



fully enlarged by the study of glacial 

 phenomena ; by that of earthquakes and 

 volcanoes ; and by that of the efficacy of 

 heat and cold, wind, rain, and rivers as 

 agents of denudation and transport. On 

 the other hand, the exploration of coral 

 reefs and of the deposits now taking place 

 at the bottom of the great oceans, has 

 proved that, in animal and plant life, we 

 have agents of reconstruction of a potency 

 hitherto unsuspected. 



There is no study better fitted than 

 that of geology to impress upon men of 

 general culture that conviction of the un- 

 broken sequence of the order of natural 

 phenomena, throughout the duration of 

 the universe, which is the great, and per- 

 haps the most important, effect of the 

 increase of natural knowledge. 



THE END. 



