41 



NOTE ON THE RECESSION OF NIAGARA FALLS. 



The question of the rate of the recession of the Falls of Niagara 

 has been the subject of much inquiry, since Lyell estimated that 

 " the cutting of the present gorge terminating at the heights 

 towards Lake Ontario had taken 35,000 years." 



Volume xix of the Yictoria Institute's Transactions (p. 90) con- 

 tains a summary of the Report of the New York Commission, and 

 diagrams therefrom ; from this Report it had been estimated that 

 the cutting had taken only 10,000 years. — Through the kindness of 

 one of the Institute's Members, Mr. Warren Upham, the Assistant 

 U.S. Government Geologist, the following particulars are given as 

 to where the results of most other surveys are recorded. 



"The early report, by Prof. James Hall, in 1842, is in The Natural 

 History of New York, Geology, Part IV, pp. 402-403. 



" In 1875 a second survey was made by the United States Army 

 Engineers. 



" The next survey was made in 1886 by Mr. R. S. Woodward, 

 of the United States Geological Survey, and his work was pub- 

 lished in New York in Science, vol. viii, p. 205. 



" Still more recent surveys have been made,* of which a more 

 important one is summarised in Science, vol. xviii, p. 216, 1891. 



" Mr. John Bogart, State Engineer of New York, has sent in a 

 report concerning the recession of Niagara Falls. In 1842 Pro- 

 fessor James Hall made an accurate survey, and a comparison 

 of his results with those in 1890, made in a bulletin of the 

 American Geographical Society, shows that the annual recession 

 at the American Fall has been 7*68 inches, and at the Canadian or 

 Horseshoe Fall, 2 feet 2*16 inches. During this period the crest 

 line of the American Fall has sunk from 1,080 to 1,060 feet, and 

 that of the Canadian has risen from 2,260 to 3,010 feet. The area 

 of rock which has been carried away during those forty-eight years 

 is 32,900 square feet at the American Fall, and 275,400 square feet 

 at the Canadian Fall. 



" In 1889 Mr. G. K. Gilbert, of the United States Geological 



* The reports of these may probably be obtained by addressing T/ie 

 State Engineer of New York, at Albany, N.Y., U.S.A. 



