150 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
carpment. To the south the escarpment, with a sUght bi*eak, contin- 
ues for a number of miles, being of moderate elevation only, but having 
lower and lower beds rise to form its face. These west-facing cliffs 
are about in line with the supposed southward continuation of the 
Sevier Fault, and would naturally be considered the face of the fault 
scarp throughout its length. As will a})pear from the accomj)anying 
sketch map (fig. C), however, the portion of the cliff-line forming the 
west side of Cedar Knoll is an erosion cliff capped by the Shinarump 
conglomerate; the fault scarp dies out near the jioint where the 
erosion scarp appears, because here relatively non-resistant beds form 
the surface on both sides of the displacement. 
The fault is easily detected on the lowland east of Cedar Knoll, 
where Triassic shales one hundred feet above the Shinarump conglom- 
erate abut against Carboniferous limestone and red shales. Even 
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Fig. D. — East-west section along line AB (figure C) showing relation of beds at 
Sevier Fault, in Cedar Knoll district. 
the transition from the weak red Triassic shales to the more resistant 
red Carboniferous shales can be readily discerned on close inspection. 
It will be seen that the beds on the down-throw side of the fault bend 
downward on a]i]>roaching the fault, as shown in Cedar Knoll (fig. D), 
while the beds on the u]>throw side are flexed upward in ])laces, — 
thus conforming to the })eculiarity noted elsewhere in the faults of the 
Grand Caiion district. 
At Cedar Knoll the beds of the downthrown side are higher than and 
overlook the beds of the upthrown side. In addition to this complete 
reversal of the topographic expression of faulting, there is an oblitera- 
tion of all topographic effect of faulting northeast of the knoll, where the 
beds on both sides of the fault line are weak shales; while southwest 
of the knoll the cliffs are traversed by a stream channel which drains 
a large area of the downthrown rocks west of the fault, through a 
narrow gorge cut in the cliffs, to the upthrown x'ocks east of the fault. 
