124 HalVs Remarks on Niagara Falls 



than it is farther up the stream, we may infer that the action 

 of the sea has had nothing to do with its excavation. 



So far as our present knowledge extends, regarding the 

 mode of excavation by streams, conjointly with the action of 

 the sea upon cliffs, I consider the question regarding Niagara 

 as settled ; both by the analogy thus afforded, and by the ex- 

 amples of streams passing over the same succession of rocks ; 

 as the Oak Orchard creek and the Genesee river. The nar- 

 rowness of the chasm from Lewiston to the site of the present 

 cascade, the nearly perpendicular sides, and the absence of 

 drift within its banks, are strong negative facts in support of 

 the proposition. The evidence that the falls are now reced- 

 ing, and the incontestible proof that they have receded con- 

 siderably since this region has been inhabited, are positive 

 facts in favor of the hypothesis. Within four years, a large 

 triangular mass has disappeared from the top of the American 

 fall, and the outline is becoming more ciu'ved. At several 

 successive periods, large masses have fallen from the table 

 rock, on the Canada side, which has considerably changed the 

 outline of the fall. 



There is still further evidence that the waters of the Ni- 

 agara river have once extended much nearer to the brow of 

 the escarpment than they do at present. The nature of this 

 evidence I pointed out in my report on the fourth Geological 

 District of New York, in 1838, pages 271, 272, and 273. At 

 that time, I was not aware that the same phenomena had 

 before been noticed, though I have since learned that the ex- 

 istence of fresh water deposits in Goat Island had been men- 

 tioned some years previous. Whether the important inference 

 had been deduced from this fact or not, I do not know. 



Goat Island stands upon the top of the precipice separating 

 the two falls ; it is formed by the accumulation of gravel, 

 sand, and clay, upon the surface of the limestone, and is evi- 

 dently a portion of a once much more extensive deposit. 

 Upon the southern side of this island, where there is an es- 

 carpment, the thickness of tlie mass is about twentyfive feet. 

 The upper half of the deposit consists of coarse gravel and 

 sand, with abundance of fresh water shells of the genera 



