70 



THE CHEMISTRY OF CREATION. 



to calculate how many millions of tons of solid 

 rock the water must have worn away in the 

 time occupied in the removal of the Falls from 

 their previous to their present position. The 

 manner in which this process of disintegration is 



BIBD'S-EYE VIEW OF XIAGAKA FALLS AND COUNTRY AKOVJTD. 



effected is described by Sir C. Lyell in the fol- 

 lowing terms : " The waters, after cutting 

 through strata of limestone, about fifty feet 

 thick in the Eapids, descend perpendicularly at 

 the Falls over another mass of limestone, about 

 ninety feet thick, beneath which lie soft shoals of 

 equal thickness, continually undermined by the 



