NIAGARA 213 



Niagara above and below the Horseshoe. All along its 

 course, from Lewiston Heights to its present position, the 

 form of the fall was probably that of a horseshoe; for this 

 is merely the expression of the greater depth, and conse- 

 quently greater excavating power, of the centre of the 

 river. The gorge, moreover, varies in width, as the depth 

 of the centre of the ancient river varied, being narrowest 

 where that depth was greatest. 



The vast comparative erosive energy of the Horseshoe 

 Fall comes strikingly into view when it and the American 

 Fall are compared together. The American branch of the 

 river is cut at a right angle by the gorge of the Niagara. 

 Here the Horseshoe Fall was the real excavator. It cut 

 the rock, and formed the precipice, over which the Amer- 

 ican Fall tumbles. But, since its formation, the erosive 

 action of the American Fall has been almost nil, while the 

 Horseshoe has cut its way for 500 yards across the end 

 of Goat Island, and is now doubling back to excavate its 

 channel parallel to the length of the island, This point, 

 which impressed me forcibly, has not, I have just learned, 

 escaped the acute observation of Professor Eamsay ' The 

 river bends; the Horseshoe immediately accommodates it- 

 self to the bending, and will follow implicitly the direction 

 of the deepest water in the upper stream. The flexures of 

 the gorge are determined by those of the river channel 

 above it. Were the Niagara centre above the fall sinuous, 

 the gorge would obediently follow its sinuosities. Once 



1 His words are: "Where the body of water is small in the American Fall, 

 the edge has only receded a few yards (where most eroded) during the time that 

 the Canadian Fall has receded from the north corner of Goat Island to the 

 innermost curve of the Horseshoe Fall." Quarterly Journal of Geological 

 Society, May, 1859. 



