PLATEAUS AND HOG-BACKS. 169 
It will be remembered that in the description of the country lying to 
the north of Red Canon and Brown's Park, it was explained that ridges 
were formed by the unequal progress of erosion through the upturned edges 
of the formations lying on the flank of the fold. 
Thus ridges are seen where the dip of the rocks is at a higfc angle 
often twenty to forty five degrees; but where the dip is at a low angle from 
one to five degrees such ridges are not found; the cut edges of the forma 
tions stand in steep escarpments, or lines of cliffs, while the slope of the 
summit of the formation is very gentle, so that when you climb one cliff the 
descent is almost imperceptible to the foot of another. (Compare lines of 
cliffs, seen in Figure 61, with hog-back cliffs, seen in Figure 52.) 
In passing through the last three canons, we have observed that the 
rocks have thus gently dipped to the north, and so, in following the river to 
the south, we are constantly running into rocks of lower geological position 
and greater age. In this way we are able to study successive beds from 
higher to lower, as we would should we descend a shaft many thousands of 
feet in depth, as previously explained. 
Expand a fold like that of the Uinta Mountains, where the rocks dip 
from ten to ninety degrees, to a more gentle curve, where the rocks dip at 
a much smaller angle, so that the inclination is scarcely perceptible to the 
eye, and can only be determined by an extended leveling and tracing 
of the strata, and the hog-backs are thrown farther apart. The escarpments 
of these hog-backs, facing the axis of the fold, are still lines of cliffs; but 
the slopes on the opposite sides are so gently inclined as not, at once, to be 
apparent, and the streams heading near the brink of the cliffs, and running 
down the gentle slope away from this line, excavate their own valleys and 
canons, and so break up the plane of this slope that its inclination is not at 
once observed; in fact, it can only be discovered as a generalization from a 
careful study, and such an inclined plateau, when seen from the side away 
from the axis of plication, would usually be considered a range of mount 
ains. Yet it has some features which readily distinguish it. The peaks 
are low mountains and hills, bordering the foot of the slope, and the table 
lands are beyond and above them, near the crest of the cliffs which face the 
axis. 
22 COL 
