THE HURRICANE FAULT. 
115 
the downward flexure has insured the preservation of a narrow strip of 
the Permian beds at the base of the Hurricane Ledge. The normal profiles 
produced in the cliff by erosion are such that the Permian strip receives 
protection from the talus. The explanation of this peculiar arrangement 
may be as follows. We may suppose that before the fault was started the 
beds along its course had been bent into a monocline dipping to the east. 
Such monoclines are the commonest and most typical form of displacement 
in the Plateau Country, and, though it would be out of place here to discuss 
the matter at length, I suspect that they are much more common in other 
regions, especially in little disturbed regions, than is generally supposed. 
The existence of such a flexure would leave the Sheavwits platform much 
higher than the Uinkaret. We may suppose the Uinkaret to have been 
hoisted above the Sheavwits after the formation of the flexiu-e, or, in brief, 
that the flexing of the beds antedates the fault. This seems very simple, 
and natural enough, nor does any other explanation suggest itself ; but this 
identical feature is repeated over and over again in other lines of displace- 
ment. It is seen in the southern part of the great Sevier fault at Pipe 
Spring, in the West Kaibab fault, and in numerous places along the great 
dislocations in the terraces and High Plateaus. If the explanation be a 
true one, it thus assumes a high degree of interest. Powell has long since 
remarked the homology between faults and monoclinal flexures by showing 
that they often shade into each other; but in such cases the shearing couple 
has the same movement, whether the displacement be flexure or fault. In 
the Hurricane the movement of the shearing couple in producing the 
monocline is reversed in the formation of the fault. 
Let us now look at the features which the Hurricane fault discloses 
along those portions of the Uinkaret which have been the scene of volcanic 
activit3^ These are admirably revealed in the Queantoweap Valle}^ This 
valley is almost the exact counterpart of the Toroweap, repeating the feat- 
ures of the latter with singular accuracy. It is a lateral vallej" excavated 
upon the sunken side of the Hurricane fault, and cuts through the upper 
and most of the lower Aubrey groups of the Carboniferous, and opens upon 
a wide esplanade of the Grand Canon, just as the Toroweap does. The 
inner gorge of the canon, however, is much less profound here; the espla- 
