84 NEW YORK STATE MUSEUM 



The former makes the age of the gorge in round numbers 32,000 

 years, the latter places it tentatively at 50,000 years, though recog- 

 nizing the uncertainty of many of the elements which enter into his 

 calculations. Prof. G. F. Wright has recently applied a most in- 

 genious method to the solution of this question, and one which 

 seems to eliminate the doubtful factors.^ This method is based on 

 the measured rate of enlargement of the oldest part of the gorge by 

 atmospheric action. The present width of the river at the mouth 

 of the gorge is 770 feet, and Prof. Wright thinks that it was probably 

 not less at the time when the formation of the gorge began. 

 Assuming that the bank at that time was vertical, he finds 

 that since then the stratum of Lockport limestone at the top 

 has retreated 388 feet. Careful measurements show that the 

 total amount of work accomplished here by the atmosphere 

 since the beginning of gorge formation, was the removal from 

 the side of the gorge of a mass of rock constituting in section 

 an inverted triangle 340 feet high and with a base of 388 feet. This 

 would be similar to a mass with a rectangular section of the same 

 hight but with a base 194 feet wide. The rate of waste of the 

 banks was measured by Prof. Wright as accurately as possible and 

 found to be over one fourth of an inch a year, or a total amount of 

 610 cubic yards of rock from one mile of the gorge wall. From this 

 he finds that 10,000 years is the maximum amount of time required 

 foT the entire change which has occurred in the bank since it was 

 left exposed by the recession of the cataract. 



The most recent and most detailed estimates of the age of the gorge 

 have been made by Prof. C. H. Hitchcock.^ He assumes that the 

 present rate of recession is four feet annually, and finds accordingly 

 that the last formed section of the gorge, from the present falls 

 to the point where it suddenly contracts above the railroad 

 bridges, was formed during 2962 years, which closely agrees 

 with Pohlman's estimate. Thus the beginning of the great 

 cataract at the northern end of the upper great gorge " dates back 

 to 1062 B.C., 300 years before the time of Romulus, or 



'Pop. sci. monthly. 1899. 55 : 145-55- 

 ^Am. antiq. Jan. 1901. 



