Science, Geology and Physics 



from 1842 to 1905 is found to be five feet per annum, with an 1907 

 uncertainty of one foot. For the thirty-three years from 1842 ' crt 

 to 1875 the rate was apparently slower than for the thirty years 

 from 1875 to 1905. The rate of recession of the American Fall 

 during the seventy-eight years from 1827 to 1905 was less than 

 three inches per annum. 



The time consumed in the recession of the falls from the 

 escarpment at Lewiston to their present position, or the age of 

 the river, is not here estimated. It can not properly be computed 

 without taking account of all conditions, local and temporary, 

 affecting the rate of recession, and some of those conditions have 

 Varied greatly from point to point and from time to time. 



GILBERT, Grove Karl. The rate of recession of Niagara Falls — I. 

 (Sci. Am. sup., Apr. 20, 1907. 62:26157-26160.) 



GILBERT, Grove Karl. The rate of recession of Niagara Falls — II. 

 (Sci. Am. sup.. Apr. 27, 1907. 63:26179-26183.) 



These articles also appear in the Annual Report of the Commissioners 

 of the State Reservation at Niagara Falls. 



[Review of Gilbert's "Rate of recession of Niagara Falls."] (Eng. 1907 

 news, Feb. 28, 1907. 57:248.) 



The rate of recession of Niagara Falls is reported on in a 

 recent bulletin of the U. S. Geological Survey by G. K. Gil- 

 bert. Surveys to determine the outline of the crest of the falls 

 of Niagara were made in 1842, 1875, 1886, 1890 and 1905. 

 The last was made specifically to furnish accurate data on the 

 recession or wearing of the falls ; it was thought that the increas- 

 ing abstraction of water for power generation will soon modify 

 the rate of erosive recession, so that data as to the natural rate, 

 which is of high importance to geologists, can not be calculated 

 from future surveys. The author deduces a mean rate of 5.3 ft. 

 per year for the Horseshoe Fall, and a mean rate of 0.2 to 0.5 

 ft. for the American Fall. Besides the records of the surveys 

 above noted, several camera-lucida sketches made in 1827 by 

 Capt. Basil Hall, are available. These, with other data, served 



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