a, BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
is now a waterfall ; and the channel floor up-stream and down-stream 
from the fall is now at different levels. 
A dam sixty-four feet high has been built: across the entrenched 
stream bed about a mile north of the town of Kanab ; an irrigating 
canal at about the level of the former valley floor is thus supplied with 
water for gardens and fields in and near the town. Since the erection 
of the dam, the depth of water in the pond above it has been much de- 
creased by inwashed waste, thus illustrating one of the most serious dif- 
ficulties — the rapid decrease of reservoir capacity — attendant upon the 
storage of water for irrigation in the arid region. 
Close by the road from Kanab to Fredonia, at the point where it 
passes through a notch in the Shinarump escarpment, a step fault is seen 
in the gray Shinarump and the uppermost chocolate Permian beds, with 
a total uplift of not more than a few hundred feet on the east. The shat- 
tered parts of the escarpment has a breadth east and west, across the 
fault, of about a quarter of a mile, and six or more separate fractures 
occur within this distance. The apparently vertical slabs between the 
fractures appear to have been sheared so as to give their strata a dip of 
about thirty degrees to the west. 
Tus Fauur ar Pirk Serine. — The outline map of the district around 
Pipe spring given in my previous paper (b, Fig. 7) may be here replaced 
by Figure 4, altered from its predecessor in several details, the most im- 
portant of which concerns a branch fault with which the Pipe spring 
monocline is to be associated as a local feature; but full confirmation 
may now be given to my former conclusion that the Sevier fault con- 
tinues its course at least ten or fifteen miles further south-southwest 
and that it is so old that the hard Triassic sandstones of the Vermilion 
cliffs in the eastern or uplifted (Kanab) plateau block have been worn 
back at least ten miles more than the same sandstones have retreated 
during postfaulting time in the western (Uinkaret) block. The latter 
point is of prime importance from its bearing on the date of the fault. 
At the time of faulting, it may be provisionally assumed that the Ver- 
milion cliffs were essentially in line on the two sides of the line of frac- 
ture. The cliffs on the west of the line are retreating actively to-day 
and have undoubtedly retreated over a considerable distance since the 
faulting occurred; but the cliffs on the east of the line, uplifted with the 
eastern block and therefore more exposed to sapping by the underlying 
clays, have retreated so that they now stand ten miles north of the re- 
treating western cliffs. This fact alone suffices to throw the date of 
faulting far back in the plateau cycle. 
