[schofield] 



ROCKY MOUiNTAIN TRENCH 



87 



3. The "Big Bends" in the Fraser and the Columbia are striking 

 and abnormal features. 



4. The Kootenay River enters the trench from the east as a large 

 river cutting through the most westerly range of the Rocky Mountains 

 in the vicinity of Upper Columbia Lake and flows southward. It has 

 a gradient of 4 . 2 feet to the mile and flows in a wide flood-plain bounded 

 by terraced banks. 



Figure 2 



5. The Columbia River rising in Upper Columbia Lake (elevation 

 2,650), pursues a very meandering course northward as far as Golden 

 (elevation 2,561) through swampy land containing many ox-bow 

 lakes. The gradient in this section is 1 . 3 feet to the mile which is so 

 small that erosion has not penetrated through the unconsolidated 

 materials to bedrock. North of Golden and around the "Big Bend," 

 the gradient is 19. 3 feet to the mile and is sufficient to cause erosion to 

 penetrate through the surface into bedrock producing a series of 

 rapids at many points along the course of the river. 



6. The Canoe River, a tributary of the Columbia from the north 

 in the trench, has a gradient from the Fraser-Columbia divide (eleva- 

 tion 2,600 feet, approx.) to its junction with the Columbia (elevation 

 2,050) of 916 feet to the mile. 



