DRAINAGE SYSTEM OF THE PARIA PLATEAU. 
201 
drainage system. We have noted upon the Kaihab that the intricate net- 
work of surface-ravines everywhere conforms to the structural and mean 
topographical slopes. Whichever way the rocks dip, that wa}^ the ravines 
run. We also noted the very striking exception of those valleys, or con- 
tinuous, single line of valleys upon the summit, of which De Motte Park is 
the most conspicuous; and we explained the considerations which led to 
the inference that the parks are the vestiges of a very ancient river valley 
existing before the development of the present structural features of the 
plateau, while the other ravines are of very recent origin and posterior to 
that structural development. In the Paria Plateau we have an analogous 
state of affairs. Its surface is covered with a network of drainage chan- 
nels, often becoming very sharp, narrow canons, cutting deeply into its 
platform. Most of these conform to the structural slope of the plateau. 
But there are two valleys which form conspicuous exceptions. One of 
these is the Paria River, which heads in the great amphitheater of the same 
name in the terraces between Table Cliff and the Paunsagunt. This river 
is everywhere independent of the structural slopes. In general it runs 
against them, but along the eastern limit of the Paria Plateau its course is 
parallel to the strike of the strata. Into this river the entire drainage of the 
plateau is gathered. Thus, while the Paria River is older than the structure 
and quite independent of it, the small surface channels of the plateau are 
quite dependent upon the structure, and no doubt are due to it. There is 
one more drainage channel of ancient date and independent of the structure. 
This is House Rock Valley, which lies along the base of the East Kaibab 
monocline. There is a very slight northeasterly dip to the whole platform, 
and against this dip both the Paria and House Rock valleys extend. The 
latter is very probably an ancient channel belonging to the same group 
of old tributaries of the Colorado as De Motte Pai’k, the Toroweap, and 
Queantoweap. For a long stretch of geological time it has been dry and 
ceased to carry water; perhaps since the first establishment of an arid climate 
in Pliocene time. But although its course is now against the dip of the 
strata it is inferred that it was not so originally, and that the displacements 
are in part at least more recent than the epoch at which the river ceased to 
flow and to corrade its channel. 
