S'6 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
land of Permian clays east of the fault, the drainage flowing from the 
depressed to the elevated block. Third, where resistant members are 
faulted opposite to weak members, the resistant member forms an upland 
on one side of the fault overlooking the lower land eroded on the weak 
member on the other side of the fault ; and this entirely independent of 
the heave and throw of the displacement. Thus the Triassic upland of 
the eastern block overlooks the lower land of Long valley, which I 
presume is eroded on the weak upper Trias ; and the Shinarump of the 
eastern block overlouks, from a modest height to be sure, the lower land 
of the weak Triassic clays in Moccasin valley. In both these cases, the 
upland of resistant rocks is in the uplifted block. On the other hand, 
the Triassic upland of the western block overlooks lower lands of lower 
Triassic and Permian clays east of Pipe spring in the eastern block ; and 
the strong Shinarump upland by Yellowstone spring overlooks the broad 
lower land of the lowest Permian layers in the eastern block. In both 
these cases, the effect of the fault is topographically reversed : the upland 
of resistant rocks is in the relatively depressed block; the relief is in 
spite of the fault and is evidently due entirely to erosion. 
It follows from what has just been said that whatever arrangement 
of drainage may have been for a time consequent on the topography 
initiated by faulting, that arrangement is now replaced by a new one 
adjusted to the faulted structures. Stream beds and the general “ wash” 
of the surface frequently cross the fault line, as often from the thrown to 
the heaved side as from the heaved to the thrown side. An example of 
this kind was described in my previous report (b, p. 128) from the neigh- 
borhood of Pipe spring, of special interest from the activity with which 
the “wash” that flows eastward across the fault from the thrown to the 
heaved side is undercutting and gaining area from the higher-lying west- 
ward wash. The divide between the two drainage areas is a low east-facing 
escarpment, known as Cedar ridge, now migrating westward and at a 
relatively rapid rate. It was seen only from a distance in 1900, but was 
visited in 1902. The-varicolored lower Trias shales are here much better 
exposed than at any other point in the district. There can be no ques- 
tion that my previous interpretation of this divide was correct, and that 
the occurrence of such a divide draining towards and migrating away 
from the heaved block, is entirely inconsistent with a recent date for the 
fault at Pipe spring. There can therefore be no doubt that the Sevier 
fault hereabouts as well as at Upper Kanab is of considerable antiquity : 
it cannot be dated in the canyon cycle, but belongs rather early in the 
preceding plateau cycle. 
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