WarRD.] THE SOUTHWESTERN AREA. 821 
iferous limestones which overspread the Colorado and Kaibab plateaus 
and stretch away for many miles to the south and southeast, but the 
presence of Permian and Mesozoic remnants in many parts of this 
great Paleozoic terrane is one of the best-attested facts in the geology 
of this region,’ and its importance as constituting the principal evi- 
dence of the former integrity of the sedimentation over this entire 
country has not been overlooked. 
_ East of the volcanic area on its south side the descent to the Little 
Colorado is on an average about 40 feet to the mile, but the dip of the 
strata is still greater, and the Carboniferous passes under the red 
shales of the next overlying formation before the bed of that stream 
is reached. This holds true for the lower portions of the river at 
least as far northwest as the crossing of the Lee’s Ferry road, 30 miles 
above its mouth. 
I examined these.red sandstones and shales on the left bank of the 
river from Winslow to a point 40 miles below, which practically cor- 
responds to the space between Camp 89 and Camp 85 of the Ives 
Expedition, and I found scattered blocks and small pieces of fossil 
wood at many points. They were usually weathered out and lay on 
the surface, and may have all been below the horizon in which they 
were actually embedded, but the evidence that they belonged to the 
formation in which they were found is strong. The fact that this wood 
is not found on the Carboniferous terrane to the west, but is met with 
only in the sandstones, confirms this view and makes the assumption 
that it belongs to a higher formation which formerly overlay them 
improbable, to say the least. No such assumption could arise but for 
the fact that almost all the geologists who have treated the region 
have referred these saliferous red sandstones to the Permian. If they 
are such the wood also is probably Permian. 
Below this point for many miles the east side of the valley is covered 
with a sheet of lava and black basaltic rock, and the surface on both 
sides is strewn with black bowlders of all sizes, which at Black Falls 
form the bed of the river. On the right bank, however, there arise 
terraces several hundred feet high, presenting bold escarpments of 
brownish-red sandstones, with occasional white limestone and gypsum 
beds and variegated marls. One of the gypsum beds is 10 feet in thick- 
ness. . Petrified wood occurs at nearly all points, and I observed many 
logs in place. Still farther down on the same side, and for more than 
10 miles above and below the crossing of the Lee’s Ferry road, there 
is an exceedingly interesting series of buttes, consisting of remnants 
of the mesa on the northeast, which rises in successive terraces some 
thousand feet above the river bed, the nearest bluff being 150 feet 
high. Scattered over the plain at its base, with a width of more than 
1 Tertiary history of the Grand Cafion district, by Clarence E. Dutton: Mon. U. S. Geol. Survey, 
Vol. II, Washington, 1882, 4°, pp. 46, 68, 117ff. 
20 GEOL, PT 2 21 
