Niagara Falls 



1903 on th e varying conditions of the Niagara history) we may place 

 p * m in round numbers as between 5,000 and 10,000 years, is at the 



same time the duration of the period since the end of the Ice age, 

 or, speaking more definitely, since the retreat of the continental 

 glacier from the northern United States and Canada. It may 

 be so accepted with confidence, for it agrees with the estimates 

 and computations independently made for the same period by 

 Prof. N. H. Winchell, from the recession of the Falls of St. 

 Anthony; by Andrews, and recently also by Leverett, from the 

 shore erosion of Lake Michigan and the accumulation of sand 

 at its south end; by Wright, from the filling of depressions among 

 kames and eskers, and from erosion by streams tributary to Lake 

 Erie; and by Prof. B. K. Emerson, from postglacial deposition 

 in the valley of the Connecticut river. In Europe, likewise, 

 numerous estimates of the lapse of time since the glacial period, 

 as collated by Hansen, are found to be comprised between the 

 limits of 5,000 and 12,000 years, being thus well harmonious 

 with the measure given us by Niagara Falls. 



In accordance with the ratios of the relative duration of pre- 

 ceding geological periods and eras, having found the approxi- 

 mate measure of the latest term in the series, namely this post- 

 glacial period, as about 7,000 years, we may well estimate the 

 whole Quaternary era, including the Ice age, as about twenty 

 times longer, giving to this era some 1 50,000 years. . . . 



With the past labor of Niagara Falls thus reviewed, showing 

 the river at its unfinished task, our investigation is led forward to 

 inquiries concerning the future. Here the popular mind, 

 impressed by the power of the cataract, and disturbed by predic- 

 tions of its changes and their results, however remote as meas- 

 ured by centuries and thousands of years, has suffered much fore- 

 boding. Without full or clear understanding of the dreaded 

 results, the common people have said, like the poet Burns, 



" Forward, though I canna see, 

 I guess and fear." 



652 



