THE DRAINAGE SYSTEM OF THE KAIBAB. 
195 
Thus, the destruction of this ancient tributary, itself a member of the 
early Tertiary river system, is associated with the movement which uplifted 
the Kaibab, and with the great monocline by which that movement is indi- 
cated and in part measured, and the epoch of these events relatively to the 
age of the river is also determined. The validity of this reasoning is attested 
by a great and complex aiTay of facts, and it brings into wonderful har- 
mony and order a mass of observations which otherwise are inexplicable. 
At the risk of becoming prolix, I venture to cite some examples of facts 
which give independent support to the conclusions just drawn. 
The whole surface of the Kaibab is covered with a maze of ravines, of 
which a description has already been given in Chapter VII. These are de- 
lineated with great care by Mr. Bodfish in Atlas sheets 11 to 14 inclusive. 
Those which are found upon the western side of the De Motte Park radiate 
away from it in all directions between northwest and south-southwest But 
not one of them flows into the park. On the eastern side there are two dis- 
tinct groups of drainage channels separated by a subordinate watershed, or 
divide, which extends from the summit overlooking De Motte Park east- 
ward to the brink of the plateau. The northern plexus flows eastward and 
northeastward ; the southern plexus flows southward and southwestward. 
The former passes down into vast gorges and amphitheaters cut into the 
great monocline and debouches upon the Marble Canon platform ; the lat- 
ter descends into the amphitheaters of the Grand Canon. The origin of 
these innumerable ravines is apparent at a glance. With a very few ex- 
ceptions, they all follow the structural and general topographical slopes of 
the plateau. If they could all be filled up again and the siu-face of the 
country smoothed off evenly with the siu’face of the upper Aubrey lime- 
stone and then left to the action of copious rains, the ravines would form 
anew and the new ones would have nearly the same general arrangement, 
the same general courses, the same general aspect, as those which now 
exist. Some slight structural changes may have occurred since the present 
channels were formed, and these might produce differences in the supposed 
new arrangement, but they would be of small amount. What better evidence 
than this could there be that these ravines were laid out and cut after the 
