in the Formation of Falleys. 457 



In some cases, indeed, the capacious magnitude of the 

 valley, compared with the diminutive size of the stream, 

 might arrest our belief of so trivial an agent having accom- 

 plished so great a work ; but those occasional and powerful 

 floods to which every brook is subject, the immense dura- 

 tion of the- action, and the yielding nature of the earthy 

 materials removed, are amply sufficient to suppress- every 

 doubt and to reconcile every difficulty. 



There are multitudes of other practical facts which the 

 actual survey of the course of streams readily supplies, and all 

 of them speaking the same forcible language, of the streams 

 themselves being the only agents that have broken down 

 the opposing obstacles in their course and reduced their 

 channels to the regular gradation slopes down which we now 

 find them flowing. 



Those who may be desirous of verifying these observations 

 on the formation of valleys, have only to visit the spring- 

 heads of their neighbouring streams, tracing the channel 

 downwards, and they will find little difficulty in marking 

 the site of every former lake and waterfall, by only sup- 

 posing the valley which lies before them to be tilled up; 

 and the obvious effect will be a lake at the upper and a 

 waterfall at the lower end : and a proper examination of 

 the soil below every valley will discover the very materials 

 formerly brought down when the valley was excavating. 



The very intimate connection between waterfalls and lakes, 

 and their disappearance together, by the former effecting 

 breaches into the latter, has been very fully dwelt upon ; and 

 accordingly where waterfalls now abound, there ought to be 

 a corresponding abundance of lakes ; and this is strikingly 

 corroborated by the fact. Canada is productive of the most 

 numerous and celebrated waterfalls, and there also, ahove 

 these falls, are the most numerous and most extensive Jakes 

 on our globe. 



Every waterfall that now exists is produced by a stratum 

 of rock crossing the course of the stream, and it is solely 

 owing to the indurated durability of the rock, that we now 

 find a fall where we should otherwise have found a valley. 

 Tins is so evident, that many of our most celebrated water- 

 falls 



