Niagara Falls 



1898 who from the evidence of the beaches, especially the Iroquois, 1 

 pencer found that the rate of recession must have been for long ages 



much less than now, on account of the interior height of the 

 falls; and also on account of the greatly diminished volume of 

 water, owing to the overflow of the upper lakes to the north- 

 east, until in recent days. But how much of the work of the 

 falls had been done before the upper lakes were turned into 

 the Niagara drainage, for a long time seemed undeterminable, 

 until the features of Foster's flats were used for measuring the 

 amount of work performed in that early episode. This standard 

 has since been confirmed by other phenomena not yet published ; 

 and from a different standpoint the distance of the early reces- 

 sion has been agreed to by Prof. Gilbert, who now considers 

 the age of the falls far greater than that formerly suggested by 

 his paper in 1886. From all the available data up to 1894, 

 the writer computed the age of Niagara Falls at 32,000 years. 2 

 Of the various episodes, that of the cataract passing the narrows 

 of the whirlpool rapids still seems the most difficult of explana- 

 tion ; but the writer has recently found that the narrows record a 

 second reduction in the amount of fall in the river, before the 

 present descent was established, thus retarding the recession 

 along this section of the gorge, and increasing in part the time 

 compensation for the reduced amount of work performed. 

 However, further discoveries are necessary to fully explain the 

 phenomenon of the narrows. It now seems probable that the 

 error in determining the time required for the recession of the 

 falls through the section of the whirlpool rapids would not affect 

 the computation of the whole age of the river by more than a 

 few per cent. 



No less important than the determination of the age of the 

 river was that of the date when the waters of the Algonquin basin 



1 Trans. Roy. Soc. Can., 1889, p. 132. Proc. A. A. A. S., 1 

 p. 199. 



2 Duration of Niagara Falls. Am. Jour. Sci., vol. XLVIII. 1894. 

 pp. 455-472. 



622 



