SURVEY OF THE COLORADO OF THE WEST. 
17 
river from Green River City to the heart of this range, we find a suc- 
cession of beds 27,000 feet in thickness including rocks from the Miocene 
Tertiary to the Silurian. On the north flank of the range we have an 
extensive development of crystalline schists. 1 considered them to be- 
long to the same horizon as the nou-conformable beds immediately 
below the carboniferous rocks elsewhere exposed in the canons, and 
further that I could trace the metamorphism laterally into these rocks 
through a series somewhat like this — gneiss, plicated schists with veins 
of quartz, quartzites, and regularly bedded sandstones, in that por- 
tion of the canon where no metamorphism is seen, I obtained 11,000 
feet of these beds. In this district our work overlaps that done by 
parties directed by Clarence King. 
The grand fold of the Uintah Mountains is greatly complicated by a 
series of transverse and oblique minor folds, some of which are anticli- 
nal, others monoclinal. Our general section on the river, with a num- 
ber of minor sections in various directions, together with the colored 
geological maps of the mountains, will explain this complex system of 
corrugations ; and, what I have considered of equal importance, the 
progress and extent of erosion which is here exhibited on a vast scale 
since the region was left by the retiring sea. 
Going on south we pass a synclinal trough marked, topographically, 
by the valley of the Uintah River, coming down from the Wasatch 
Mountains on the west, and by the valley of White River, coming down 
from the Rocky Mountains on the east. 
Still continuing to the south, we find rocks dipping to the north, and 
in our progress down the river we pass a succession of. underlying beds 
until we find about 8,000 feet of Tertiaries at the foot of the Canon of 
Desolation, then, 2,500 feet of Cretaceous rocks at the foot of Gray Canon, 
nearly 2,000 feet of Jurassic, and an equal amount of Triassic at the foot 
of Labyrinth Canon, when we once more enter beds of Carboniferous age. 
In descending through Still- Water Canon, and the upper half of Cat- 
aract Canon, we run into a great fold the axis of which is probably 
marked by the Sierra La Sal. Then we turn through the lower end of 
Cataract Canon and Narrow Canon until we pass out of the fold on the 
sameflankby which we entered it, and once more find beds of Triassic age. 
From this point to the southern extremity of the great system of south- 
ern plateaus, marked by a line of eruptive mountains, of which San Fran- 
cisco Mountain is the culminating peak, the general dip of the formation 
is to the north, extending from a line some distance to the east of the 
Colorado, and westward to the foot of the Pine Valley Mountains; but 
this general slope is greatly modified by another, and doubtless later 
systems of displacements which have northerly and southerly axes. 
These displacements are either faults or monoclinal folds. I shall recur 
to them again. 
Descending the Colorado through Glen Canon, we find this chasm 
to be cut through rocks of Triassic age developed to a thickness 
2 C W 
