210 FRAGMENTS OF SCIENCE 



dissolved; but added to this we had the action of the 

 sand and gravel carried along by the water, which, on 

 striking the rock, chipped it away like the particles of the 

 sand-blast. Thus, by solution and mechanical erosion, 

 the great chasm of the Finsteraarschlucht was formed. It 

 is demonstrable that the water which flows at the bottoms 

 of such deep fissures once flowed at the level of their 

 present edges, and tumbled down the lower faces of the 

 barriers. Almost every valley in Switzerland furnishes 

 examples of this kind; the untenable hypothesis of earth- 

 quakes, once so readily resorted to in accounting for these 

 gorges, being now for the most part abandoned. To pro- 

 duce the cafions of Western America, no other cause is 

 needed than the integration of effects individually infini- 

 tesimal. 



And now we come to Niagara. Soon after Europeans 

 had taken possession of the country, the conviction ap- 

 pears to have arisen that the deep channel of the river 

 Niagara below the falls had been excavated by the cata- 

 ract. In Mr. Bakewell's "Introduction to Geology," the 

 prevalence of this belief has been referred to. It is ex- 

 pressed thus by Professor Joseph Henry in the "Transac- 

 tions of the Albany Institute" : ' "In viewing the position 

 of the falls, and the features of the country round, it is 

 impossible not to be impressed with the idea that this great 

 natural raceway has been formed by the continued action 

 of the irresistible Niagara, and that the falls, beginning at 

 Lewiston, have, in the course of ages, worn back the rocky 

 strata to their present site." The same view is advocated 

 by Sir Charles Lyell, by Mr. Hall, by M. Agassiz, by Pro- 



1 Quoted by Bakewell. 



