24? Mr. Fairholme on the Falls of Niagara. 



This rapid slope, however, is by no means precipitous: it 

 extends across the river on both sides, and is covered with 

 forests and vegetation. It is from this point that the section 

 made by the river takes its rise ; and instead of so long a rapid 

 as I had at one time been led to imagine, I have now reason 

 to believe that the primitive rapid was chiefly over the super- 

 ficial slope of Queenston heights, and that the form of the 

 section would therefore be more correctly drawn thus, 



than as given in p. 17. 



It may be urged that this addition to the work to be per- 

 formed must make a vast difference in the time required for 

 the execution of it. This is not the result, however, in this 

 case, although in common circumstances it might be so ex- 

 pected. But it has been observed by the same persons to 

 whom I am so much indebted for this correction, that in the 

 case of Niagara, my computation, as to time, has every ap- 

 pearance of being exceedingly correct. Not only is the deep 

 ravine already cut out much narrower below the falls than at 

 the cataract itself, but the crumbling shale which forms the 

 lower part of the rock at the falls, forms, lower down, a much 

 greater proportion of the whole rock. At the falls, the depth 

 of the solid limestone is 70 feet, the whole of the remainder 

 being of the soft nature of shale ; towards Queenston, the 

 superincumbent limestone is much thinner, and the action of 

 the water upon the whole body of the rock must have been 

 consequently much more rapid. 



Again, as to the actual cubic measurement influenced by 

 the river's action lower down, as compared with what it now 

 is at the falls, there is a difference so great, that it would 

 compensate for even a greater additional cubic body of rock 

 than I have now found it necessary to add to my former 

 calculation. The width of space over which the river's action 

 is now spread, including Goat's Island, is about 3500 feet, 

 and over this wide space, we find that the fall is retrograding 

 at the rate of nearly four feet per annum. But the medium 

 width from the falls to Queenston is not more than about 

 \Z00 feet, in some places more, in some less; and when this 

 greatly inferior width is added to the softer nature of the 

 rock already alluded to, we cannot doubt that the action was 

 much more rapid in the early periods of the section, since the 

 quantity of water must always have been what it now is. 



We might, therefore, even in the absence of all other evi- 

 dence, safely assume that the time necessary for the comple- 

 tion of this vast natural work could not be extended much 

 above 4000 years. When this remarkable fact is corroborated, 



