Science, Geology and Physics 



gorge. Since that time the operative power of the water, has 1831 

 spread itself over a greater surface; for the stream on the Ameri- stonehau h 

 can side, is 1 072 feet wide, and the curvature of the great Horse 

 Shoe fall is 2376 feet wide, making a surface of 3448 feet long, 

 being near three times the extent of the line it previously exerted 

 itself upon. 



This diminished exertion would necessarily be attended by a 

 retardation in the retrocession of the cataract. There is also 

 another circumstance which at present adds to this cause of 

 retardation. The Horse Shoe fall has reached a point, where 

 the limestone beds begin to thicken, and the foam of the rapids, 

 marks the presence of the terraces of cherty layers, which are 

 here found superincumbent, and giving additional strength and 

 durability to the limestone strata. I might offer as evidence of 

 the very prolonged projection of the waters at this point, the deep 

 basin in the bed of the river, immediately at the foot of the falls, 

 which does not occur in the narrower parts of the gorge, and 

 which has hitherto been unaccounted for. 



It has often been proposed to mark in some well regulated 

 manner, the future disintegration of the bed of this cataract, with 

 a view to compute the period of its age. If I have not miscon- 

 ceived the operation of this river, it will now be seen that the 

 elements of this problem are too complicated and vague, to offer 

 any hopes of a satisfactory solution. Under the view I have 

 taken of it, its future recession will be very slow. Time, how- 

 ever, will last longer than the carboniferous limestone can prob- 

 ably resist such influences as it has already yielded to. When 

 the cataract shall reach lake Erie, geology will possess one great 

 monument of the power of water to excavate gorges of great 

 length and height. 



Mr. Lyell, in his principles of Geology, (1:181) has, — 

 supposing that the disintegrating power of the volume of the 

 Niagara river, will at all times be equal, at every point of its 

 course — ventured on a computation, that, at the rate of fifty 

 yards in forty years, lake Erie will be reached in the course of 



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