286 Mr Forstcr on the Falls of the Niagara, 



depth was, I cannot help believing, probably the commencement 

 of the present remarkable trough below the falls.* 



Ill the present very imperfect state of information respecting 

 the superficial deposits around the shores of our western lakes, 

 it is out of our power to do more than conjecture the geological 

 era of the supposed retreat of the waters, which appear to have 

 covered at one time the vast plains surrounding them. Whe- 

 ther such an event were caused by the general rush of waters 

 from the north, or whether it is to be viewed as having occurred 

 subsequently, we have no means of judging. -f 



There is this important fact, however, that none of the supe- 

 rior secondary or tertiary formations of our Atlantic coast, 

 have been discovered in the region of these lakes, shewing 

 clearly that all that portion of the continent emerged from be- 

 neath the ocean at a very remote period. The drainage of the 

 region has very properly been repeatedly modified since that day, 

 and during some or perhaps several of these changes in its hydro- 

 graphy, Niagara acquired its present remarkable shape. 



If any credit be due to the consideration here advanced, it 

 must be obviously improper for geologists to aim at computing 

 the time which the Niagara river has consumed in excavating 

 its way to the spot where it now pours off its waters, since to as- 

 certain what portion of the ravine below the Falls may have re- 

 sulted from other causes than the cutting power of the stream, 

 is clearly beyond our ability. 



It is an observation of Professor Sedgwick, that the existing 

 valleys of any country are generally the result of the joint 

 agency of many causes, and the remarkable valley of the Nia- 

 gara river, notwithstanding the simplicity of its features, may 

 exemplify this principle. 



• Mr Fairholme, in ascribing to the Niagara the duration which he has, 

 obviously regards it as post-diluvial ; he is therefore constrained to grant the 

 pre-existence of the denuding sections for which I contend. 



•f There are in the class of those who assign to it a greater age, some who 

 would be inclined to consider it as also partly ante-diluvian. To these my 

 argument is similar ; to-wit, that it is not credible that any powerful diluvial 

 current should traverse the surface of this region with the deep valley of the 

 Niagara river previously existing, without materially augmenting the length 

 and magnitude of the ravine. 



