DAVIS: THE GRAND CANYON OF THE COLORADO. a 
noted ; but when the slides advance far enough to fall over the bench, 
they flow down its frontal slope and sprawl out on the platform beneath 
like gigantic lava floods, as in Figure 5. The streams of rock-waste 
sometimes descend by a re-entrant notch in the front of the bench, like 
the lava flows in the notches of the upper Aubrey cliffs on the west side 
of Toroweap valley; they sometimes advance in large volume and 
cascade over the front of the bench, smothering salient as well as re- 
entrant of the Shinarump. ‘The different colors of successive strata are 
normally arranged in orderly bands on the face of the cliffs ; reddish 
gray sandstones at the top, then red-and-yellow-brown sandstones — 
vermilion seemed to us too strong a name for these cliffs, and ‘ freight- 
car red” was suggested as a substitute —blue in the lower Triassic clays, 
chocolate brown in the Shinarump cliff, and banded creamy gray in the 
upper Permian slope. Something of banded colors may still be seen in 
the slides that have moved down and forward in orderly fashion to form 
the monoclinal ridges, but the color bands in the slides of greater forward 
advance become greatly confused when the slides sprawl down the Shina- 
rump bench, and a most curious patchwork of reds, yellows, blues, grays, 
and browns is the result. Most of the slides seem to be old enough to 
have suffered some erosion since their descent, yet they are young and 
large enough to be very conspicuous elements in the landscape. They 
are easily recognized when seen at a distance of eight or ten miles from 
the summit of the Kaibab, where the road crosses it westward from 
House-rock spring. 
If we now cross the river and go some twenty miles south of Lee’s 
Ferry, the blue clays are concealed under the evenly graded floor of 
a monoclinal valley that follows the foot of the Echo cliffs; the Shina- 
rump sandstone rises on the western side of the monoclinal valley, so as 
to overlap the eastern part of the Marble platform. The Triassic sand- 
stones are, however, bolder in this part of the Kcho cliffs than in the 
Vermilion cliffs of the northern part of the House-rock valley; they 
here expose a larger proportion of bare rock cluttered over with scanty 
and very coarse waste, not of orderly enough arrangement to be called 
a talus. Passing northward towards the river, the Shinarump sandstone 
crosses the valley obliquely as a low ridge, thus shifting from a cuesta- 
like attachment on the border of the Marble platform to a basal bench 
and cliff at the foot of the Echo cliffs; at the same time, the monoclinal 
valley shifts from the blue clays of the lower Trias to the weak Permian 
strata. Thus the blue clays come to outcrop on the slopes beneath 
the red sandstones of the Echo cliffs, and at once the landslides begin. 
