88 THE ROYAL SOCIETY OF CANADA 



7. The McLennan River which flows northward to join the 

 Fraser in the trench from the Fraser-Columbia divide has a gradient 

 of 25 feet to the mile. 



8. The Fraser River is described by Malloch^ in the following 

 words : 



"Topographically, the portion of the Fraser valley examined 

 falls into two main divisions. From Tête Jaune Cache down to the 

 Grand Canon — 100 miles above Fort George — it runs between two 

 parallel ranges of mountains, while for the remainder of the distance 

 it traverses the Interior Plateau, where the hills are irregularly dis- 

 tributed, and usually cannot be seen from the river. The trough which 

 the Fraser occupies in the first of these topographic divisions is one of 

 the striking features of the mountainous region of eastern British 

 Columbia. It extends from the International Boundary northwest 

 for 800 miles, and in origin is evidently quite independent of the 

 present drainage system; for in it the Kootenay, Canoe, and Findlay 

 Rivers flow southeast, and the Columbia, Fraser, and Parsnip, north- 

 west. Moreover, the trough, at the divides between the different 

 drainage systems, is as wide and has as gentle a slope as where it is 

 occupied by any of the large rivers mentioned. This is well exempli- 

 fied at Tête Jaune Cache, where the Fraser enters the trough from the 

 east, and where, although the part below the elbow is drained by a 

 small tributary only, carrying about one-tenth of the amount of water 

 in the main river, the trough is not contracted nor the gradient changed. 



On the other hand, the lateral tributaries of the Fraser break 

 through narrow gaps in the side walls of the trough and have steep 

 gradients until they reach the strip of flat land which lies along the 

 river. This strip is from 3 to 5 miles wide, while the distance across 

 the trough from peak to peak averages about 10. The ranges flanking 

 the trough are lower than the succeeding ones, and decrease in height 

 from Tête Jaune Cache to their northern ends near the Grand Canon. 

 At the former place they rise 7,000 feet above the valley, while near 

 the latter they are not much more than 4,000 feet above it. There is, 

 however, a break in this general decrease in height. The range on 

 the northeast side at a point opposite the mouth of Goat River, and 

 the range on the southwest side at a point below the gap of Dome 

 Creek, suddenly increase in elevation. From these points the ranges 

 become lower, but the rate of decrease is much more rapid on the 

 southwest side, so that the range there ends above the Grand Canon ; 

 whereas the range- on the other side extends to Toneyquah Creek. 

 From the river a few glimpses were caught of a long range extending 



1 Malloch, G. S., Geol. Surv., Can., Sum. Rept., 1909, p. 123. 



