1894.] The Duration of Niagara Falls. . 861 
of Lake Erie and the Niagara. Under these conditions only 
Yr of the present discharge of the Niagara River cascaded over 
the falls. The episodes of the river are as follows: First epi- 
sode: water descending 200 feet, volume j4 of the present 
(when the falls was of about the magnitude of the present 
American cataract) chasm excavated (as shown by the posi- 
tion of terraces) 11,000 feet; time required, 17,200 years. 
Second episode: descent of the river in a series. of three cas- 
cades aggregating 420 feet at first with only the Erie drainage 
(during the recession of 3,000 feet) and afterwards the present 
volume of water (when the recession amounted to 7,000 feet) 
duration 10,000 years. Third episode: river descending 420 
feet in one cascade with the present volume; time required, 
for the recession of 4,000 feet, only 800 years. Fourth episode 
was somewhat complieated, with the water mostly descending 
920 feet, and during this condition the falls have receded 
11,500 feet, and required a period of 3,000 years. Thus the 
age of the falls has been computed at 31,000 years. Butat the 
beginning, the river flowed from lake to lake without a falls, 
and this time has been taken as 1,000 years; accordingly, the 
age of the river is computed at 32,000 years. The record 
of the changing levels may be seen in the deserted beaches 
now high above the lakes which have already been described 
in scientific journals. The investigations doubtless contain 
some errors which may be corrected in the future, but in 
the history of the lakes the present computations are very 
strongly confirmed by much cumulative evidence so that the 
present results appear to be approximately correct. It is fur- 
ther estimated that with the earth movements continuing as 
at present, the end of the falls will be effected by the change of 
the drainage from the Niagara River to the Mississippi, by way 
of Chicago, owing to the rise of the eastern rim of the Erie 
basin above the barrier now separating the lake waters from 
the Mexican drainage. With the present rate of elevation con- 
tinuing, the future life of the river ought to be 5,000 or 6,000 
years. 
In regard to the relation of Niagara River to the Ice Age, I 
estimate that the lake epoch commenced from 48,000 to 
