CLASSIFICATION OF VALLEYS. 161 
lesser inclination of the rocks. Second, the texture of the beds that is, 
their greater or lesser degree of heterogeneity. The third class of modify 
ing influences is found in the eruptive beds. 
The last mentioned agencies are not found in the region under imme 
diate discussion. 
No sharp line of division can Jbe drawn between canons and valleys. 
For convenience, we designate intervening depressions, caused by erosion, 
canon valleys, but all these excavated basins, troughs, and channels will be 
included under the general head of valleys, and the above terms will be 
used in describing them. 
I should remark, farther, that species are not found in structural geology, 
if we use that term as it has heretofore been used in the description of organic 
nature; that is, there are no definite "hard and fast" lines of demarkation 
between valleys of one class and those of another, and the classification 
rests solely on typical examples. 
With these terms before us, let us again describe the valleys of the 
Uinta Mountains. 
The canons through which the river passes from Flaming Gorge to Bee 
Hive Point are anaclinal. Red Canon is obliquely anaclinal; Brown's Park 
is anticlinal; the Canon of Lodore is cataclinal; Whirlpool Canon above is 
anaclinal where it runs into a fold, and then obliquely cataclinal in cutting 
through the other side of the fold. 
Split Mountain Canon is at first anaclinal, then along its central course 
anticlinal, and at its foot, where it runs out on the opposite side of the fold, 
is cataclinal; hence it is structurally compound. This is the relation it bears 
to the minor fold of Split Mountain; but it bears another relation to the 
great fold of the Uinta Mountains, and is complex. Hence it is a com 
pound, complex valley. 
The canons and valleys heading near the summit of the range running 
with the strike of the rocks into Green River, as above mentioned, are onono- 
clinal. A good example of this is Summit Valley. Those on the north, 
which head near the summit of the range, and, running down the flank, turn 
into Green River, are, in their upper courses, cataclinal, and when they turn 
to follow the strike of the rocks into Green River, are monoclinal. Those 
21 COL 
