200 
THE GEANH CaSTON DISTEICT. 
dine, which throws down the former (or more properly raises the latter) 
about 3,500 feet. The same I’elative downthrow affects in varying amount 
the Mai’ble Canon platform. 
This southward projection of the Triassic teiTace illustrates in a very 
complete manner the effect of a fault upon the recession of cliffs when the 
fault runs in a direction perpendicular to the trend of the cliffs. The cliff 
extending away from the fault on the side of the downthrow has a dimin- 
ished rate of recession. On the side of the upthi’ow this rate of recession is 
increased. The two rates are of course considered relatively to each other. 
This fact is of repeated application in the Grand Canon district, and indeed 
throughout the Plateau country generally. Along the line of the terraces 
the great faults run perpendicularly to the trend of the escai’pments, and 
the same effect is in each instance produced upon the rate of recession. A 
case quite homologous to the Paria Plateau is seen at the north end of the 
Sheavwits platform. Here the Hurricane fault throws up the Uinkaret 
side, and depresses the Sheavwits side. Upon the sunken side the Trias and 
J ura come in, occupying an area far in front of the main lines which termi- 
nate those formations upon the upthrow. Still again at the base of the 
Grand Wash fault, near the Colorado River, a patch of Trias is preserved 
under circumstances quite similar. 
The cause of this retarded rate of recession is not far to seek. It 
is merely a special case of the general law that erosion is more rapid 
{ceteris parilms) upon high levels than upon low ones. It is so for two 
reasons. In this region at least — and the same is true of most other regions 
— the rainfall increases witli the altitude. So also does the factor of trans- 
portation. For the higher the locality tlie greater are the slopes of the 
streams which flow away from it, and the more rapidly do they remove the 
debris produced by weathering. But the more rapid removal of d(^bris in 
turn quickens the rate of weathering and disintegration, for the exposure of 
the rocks becomes greater. This law is repeated over and over again, and 
its verity illustrated on every hand throughout the Plateau Province. Those 
regions which have been elevated most have been most degraded by erosion; 
and inversely. 
The Paria Plateau also exhibits some interesting facts in relation to its 
