NIAGARA FALLS AND VICINITY 85 



to the reign of King David at Jerusalem." Prof. Hitchcock be- 

 Heves that the gorge of the whirlpool rapids was formed while 

 Niagara drained only the diminished Lake Erie, and he allows a 

 period of 7800 years for the accomplishment of this task. For the 

 erosion of the remaining portion of the Niagara gorge Prof. Hitch- 

 cock allows 8156 years. Thus the total length of time required to 

 carve out the Niagara gorge is considered by Hitchcock to be 

 18,918 years. 



The reader should here be reminded that all such estimates are 

 little more than personal opinions, and that they necessarily vary 

 according to the individual predilections as to greater or less power 

 of erosion possessed by the cataract under the given circumstances. 

 The leading questions concerning the extent of the preglacial 

 erosion in this region, and the changes in volume of water during 

 the lifetime of the Niagara, which are of such vital importance in 

 the solution of this problem, are by no means satisfactorily answered. 

 Nor can we assume that we are familiar with all the factors which 

 enter into the equation. There may be still undiscovered causes 

 which may have operated to lengthen or shorten the lifetime of this 

 great river, just as there may be, and probably are, factors which 

 make any estimates of the future history of the river and cataract 

 little more than a mere speculation. We may perhaps say that our 

 present knowledge leads us to believe that the age of the cataract 

 is probably not less than 10,000 nor more than 50,000 years. 



