160 EXPLOBATION OF THE CANONS OF THE COLORADO. 
edges of the strata, and run in a general direction with the dip of the strata 
until they reach the long valleys between hog-backs, then down these valleys 
they turn, sometimes cutting through intervening ridges, until they find 
their way into the Green, where they are turned to the south, away from 
the mountain. 
It will thus be seen that the relation of the direction of the streams to 
the dip of the rocks is very complex, and, for convenience of description, I 
have elsewhere classified these valleys, on the basis of these relations, in the 
following manner : 
Order first. Transverse valleys, having a direction at right angles to the 
strike. 
Order second. Longitudinal valleys, having a direction the same as the 
strike. 
Of the first order, three varieties are noticed: 
a, diaclinal, those which pass through a fold. (Fig. 53.) 
&, cataclinal, valleys that run in the direction of the dip. (Fig. 54.) 
c, anaclinal, valleys that run against the dip of the beds. (Fig. 57.) 
Of the second order, we have, also, three varieties: 
Aj anticlinal valleys, which follow anticlinal axes. (Fig. 55.) 
Bj synclinal valleys, which follow synclinal axes. (Fig. 56.) 
(7, monoclinal valleys, which run in the direction of the strike between 
the axes of the fold one side of the valley formed of the summits of the 
beds, the other composed of the cut edges of the formation. (Fig. 58.) 
Many of the valleys are thus simple in their relations to the folds; but, 
as we may have two systems of displacements, a valley may belong to one 
class, in relation to one fold, and to another in its relation to a second. Such 
we designate as complex valleys. 
Again, a valley may belong to one class in one part of its course and 
to another elsewhere in its course. Such we designate as compound valleys. 
It will be further noticed that valleys may have many branches, but, in 
relegating a valley to its class, we consider only the stem of the valley 
proper, and not its branches. 
A great diversity in the features of all these valleys is observed. Most 
of these modifications are due to three principal causes: First, a greater or 
