RIVER EROSION 171 
thousand feet (in places more than a mile) above the 
river bed (Fig. 86). Not only is the plateau cut by 
this marvellous cafion, but it is also trenched by hun- 
dreds of less magnitude. 
Fie. &6. 
A general view of a part of the Colorado Cajion, showing the sculpturing of the 
general surface. 
In many parts of the world, similar but smaller 
examples of river erosion are found; but while won- 
derful and impressive, the Colorado is hardly more so 
than a broad river valley with gently sloping sides ; for 
if we consider that once the rocks extended entirely 
