114 
THE GRAND CANON DISTRICT. 
some places they are partially obscured by volcanic sheets, but enough of 
them is exposed to leave no doubt as to their presence Moreover, they all 
exhibit a much larger volume than the corresponding exposures further 
eastward. Unless we suppose that the inferior formations thin out or dis- 
appear as the superior ones come in, the inferred amount of displacement is 
an unavoidable conclusion. There is no apparent reason for such a supposi- 
tion, and the presumption is quite the contrary. 
Although it is going far outside of our district, it may be remarked that 
the Hurricane fault extends northward into Utah along the entire western 
front of the Markagunt, and is still apparent on the southwestern flank of 
the Tushar range, where it finally disappears beneath great floods of lava. 
Its total length is certainly more than 200 miles. Wherever it runs it 
always forms an important topographic feature, the prominence of which is 
generally proportional to the amount of displacement. At the maximum 
part it constitutes the border of the great MarkAgunt mass, and at the same 
time the border of the Plateau Province. Between the Virgen and the Colo- 
rado it is the dividing line between the Uinkaret and Sheavwits. At the 
iqflhrow is the Hurricane Ledge, which looks down 1,200 to 1,600 feet 
upon the Sheavwits platform. The cliff of displacement thus formed is 
perhaps the longest and best defined and one of the loftiest in the West. 
The details of this displacement are full of intei’est, and they are also 
extremely varied. The portion which lies along the greater part of the 
Uinkaret border is generally not very complicated, but in a few localities 
it is extremely so. From fifteen to twenty miles south of the Virgen the 
Sheavwits platform in the vicinity of the fault plane is terribly shattered 
and mangled, and it is doubtful 'whether any analysis of it here is prac- 
ticable; but the simjDle character is soon resumed, and thenceforward to the 
Colorado every phase of it is distinct. It presents a single sharp disloca- 
tion, with no apparent crushing or shattering of the beds, and the only 
noteworthy feature is the persistent way in which the beds of the downthrow 
flex downwards as they approach the fault line. In many places, also, the beds 
of the upthrow flex upward a little for a few hundred yards as they approach 
the fault, but this feature is somewhat less pronounced and less persistent than 
the opposite flexures of the dropped side. It is interesting to note here that 
