Niagara Falls 



1907 weight and fall away in large blocks. Each rock fall causes a 

 jar of the ground which is perceived by people in the vicinity, 

 and results in a modification of the crest of the cataract which 

 is readily seen by anyone familiar with its outline. Such changes 

 of the crest have been observed from time to time ever since the 

 neighboring banks of the river were occupied by white men. It 

 is highly probable that they were also observed by Indians before 

 the advent of white men, but on this point I have made no 

 inquiries, as Indian traditions are not likely to be sufficiently 

 definite to aid in determining the rate of progressive change in 

 the position of the cataract. 



The surface of Lake Erie is 325 feet higher than the surface 

 of Lake Ontario. The belt of land between them includes two 

 plains, of which the higher and broader is raised but little above 

 the level of Lake Erie, and the lower slopes gently to the shore 

 of Lake Ontario. The descent from the upper to the lower is 

 abrupt, constituting a line of cliffs parallel to the shore of Ontario 

 and known as the Niagara escarpment. The river, issuing from 

 Lake Erie at Buffalo, flows at first on the upper plain. It is 

 there broad and comparatively shallow and has no valley. At 

 the falls it suddenly drops into the head of a narrow gorge which 

 is six miles long and extends to the escarpment. Within the 

 gorge it is narrow and contained by steep walls. Near the head 

 of the gorge the water is deep, the current moderate, and the 

 descent small, but farther on are fierce rapids with steep descent. 

 Some of these relations are shown in fig. 2. As the falls are at 

 the head of the gorge, it is evident that their recession makes the 

 gorge longer. 



(Here follow citations from various authors who had observed the 

 recession of the Falls, beginning with McCauslin in 1774—1783.) 



• • • • • 



The preceding citations serve to show the early development 

 of three ideas : ( 1 ) That the crest of the Horseshoe Fall is reced- 

 ing upstream, the recession being caused by the energy of the 



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