and the Reasonings of some Authors respecting tliem. 283 



condition of our information respecting the structure of the 

 neighbouring region, such a doctrine cannot, I conceive, be 

 much more than a mere surmise ; and I hold it to be altogether 

 premature, to erect upon such grounds any calculation in years 

 of the probable duration of the cataract. The following, in the 

 words of Mr Bakewell, presents the prevailing doctrine regard- 

 ing the age of the Falls : " On viewing this highly interesting 

 scene, the mind is irresistibly carried back to the time when a 

 mighty flood poured over the once united precipice above 

 Queenstown. This fact cannot be doubted by any one who sees 

 its present appearance, and who duly reflects on what a falling 

 body of water, so immense, so rapid, and so resistless in its course 

 as the river of Niagara, is capable of accomplishing in a series of 

 ages. Taking it for granted that the Falls have been once at 

 the ridge, it is a curious question to inquire, when were they 

 there ? An approximate solution to this inquiry will be given, 

 if Mr Forsyth's statement be allowed, of the Falls having receded 

 nearly fifty yards in the last forty years, and if it be granted 

 that this has been the constant ratio of their recession. The 

 distance from the termination of the gorge to the Fall is seven 

 miles, equal to 12,520 yards, which gives 9856 years for the 

 period in which they have been retrograding to where they now 

 are/' 



Mr Fairholme, proceeding upon nearly the' same data,* en- 

 deavours to prove that its retrocession was once much more 

 rapid than at the present day, by supposing that the slope of 

 the land gave the Falls originally a less elevation, that the ex- 

 cavation was narrower, and the rocky materials more destruc- 

 tible. In answer to the views of Mr Bakewell, for whose fidelity 

 of description, so far as it goes, I have a high respect, I would 

 suggest that we are hardly entitled to assume the statement of 

 Mr Forsyth as a sufficient basis for a calculation so important 

 in its theoretical applications. 



I hold it to be impossible, with the means of measurement 

 heretofore employed, to ascertain, with any approach to preci- 

 sion, the amount of retrograde movement. Does the recession of 

 fifty yards in forty years, asserted by Mr Forsyth, apply to both 



* See London and Edinburgh Philosophical Magazine for Juty 1834. 



