52 THE ROYAL SOCIETY OF CANADA 



length of the gorge, it forms rapids and whirlpools that would swamp 

 any craft that attempted to navigate them. 



The trend of the gorge is in general north and south, but there 

 are a number of sharp bends and curves in it which, because of the 

 narrowness of the valley, appear more pronounced than they really 

 are. These curves make it impossible to obtain an unbroken view 

 of more than a small part of the gorge. The gorge lies in granitic 

 rocks of the Coast Range batholith and only in one place actually 

 enters stratified rocks. The formation of the curves, therefore, are 

 probably due to lines of weakness in these rocks such as would be 

 produced by fracturing, cleavage, or jointing. 



The most important streams emptying into the gorge are Skuzzy 

 and Spuzzum creeks on the west side and Siwash creek on the east. 

 All of these are small, rising in the mountains a few miles back and 

 descending rapidly to the Fraser river. The junction of these streams 

 with the Fraser is similar to that already described for Anderson 

 river — that is to say they occupy hanging valleys whose beds are 

 several hundred feet above the Fraser river, and whose bottoms have 

 been notched by the action of the stream so that the junction is now 

 effected through narrow rock-walled canons. 



In the case of the tributary streams entering the gorge the notch- 

 ing has not been so pronounced because of the relative smallness of the 

 streams and their inability to incise, so that these streams do not 

 enter at grade but plunge over a series of falls or steep rapids to join 

 the main stream. 



Of all the tributary streams Skuzzy creek shows the most marked 

 break in grade. Its broad upper valley joins that of the Fraser at an 

 elevation of some hundreds of feet above the bottom of Fraser valley 

 and this upper valley is sharply notched. Again, its waters flow over 

 a rock bench in Fraser valley itself and plunge directly into the waters 

 of the river. The rim of the rock bench is also slightly notched by 

 stream action. The result is that Skuzzy creek is hanging at two 

 different points in its course. Not only is its main upper valley hang- 

 ing over the main Fraser valley, but its lower notched valley is hanging 

 over the lower inner gorge of Fraser river. 



These two closely similar features though belonging to the same 

 stream have been developed under entirely different circumstances. 

 The upper hanging valley like others in northern regions may un- 

 doubtedly be attributed to glacial deepening of the main valley, 

 while the lower hanging valley, lying as it is below the limits of glacial 

 influence, owes its formation to a difference in the depths to which 

 erosion has been effected by the two streams following post-Glacial 



