~14 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
fault is here a few degrees east of north ; its displacement must exceed one 
thousand or fifteen hundred feet. The bluffs of the great Triassic escarp- 
ment —the Vermilion cliffs — are seen coming westward in the eastern 
(Kanab) plateau block from a point far beyond Kanab: they end at the 
eastern side of Long valley, about ten miles nerth of our point of view. 
A broad and gently sloping graded platform leads forward from the base 
of the Triassic escarpment to the summit of the lower Shinarump escarp- 
ment, whose promontories are seen in profile far east of Fredonia. Al- 
though irregular in detail, the general course of this escarpment is held 
until the capping sandstones are abruptly cut off on reaching the fault 
line, about two miles away to the north: this is well illustrated in Plate 
3 A. The Permian beds were well seen in late afternoon light, their 
lower and lower layers advancing in faint scarps and well-defined color 
bands five or more miles south of the Shinarump bluff, until the yellow- 
ish super-Aubrey beds appear about the head of lower Kanab canyon 
where Kanab creek cuts its way down in Kanab plateau, so as to join the 
Colorado at grade. 
Turning now to the western tieseee) block, the Triassic escarp- 
ment is seen to end eastward against the fault line at Pipe spring, 
where its margin with eastward dips lie next to the Permian clays of 
the eastern block. The Shinarump escarpment of the western block 
is seen to terminate eastward about ten miles south of Pipe spring, near 
Yellowstone spring. The relief of the escarpment there is much greater 
than that of its disconnected eastern fellow, because the graded surface 
of the plateau plain about Yellowstone spring lies much lower than it 
does further north, and a much greater thickness of Permian clays is 
therefore exposed in the strong frontal slope of the escarpment as one 
passes around its terminal bluff on the way to Yellowstone spring. As 
with the Triassic escarpment, so with the Shinarump: the retreat of its 
eastern member is some twelve miles in excess of that of its western 
member: and the latter must to-day be retreating with considerable 
rapidity, if one may judge by the fresh surface of the weak Permian 
clays under the capping sandstones. It is in these bluffs that one may 
see the slight unconformity of Shinarump on Permian noted by Dut- . 
ton (b, p. 44, 80), and here illustrated in Figure 5. 
Tue Moccasin Fauur.— The eastern border of the Triassic upland 
back of Pipe spring is indented by a flat-floored, mile-wide valley head- 
ing to the northwest. The valley may be named after Moccasin spring 
on its western side. The strong Triassic sandstones are locally bent 
down so as to dip 10° or 20° northeastward as they descend toward the 
