1877. ] Explorations in Colorado. TT 
The Grand River from the mouth of the Gunnison River to 
that of the Dolores, that is, for nearly a hundred miles, flows along 
the southern edge of a broad valley, much of the way being in a 
low cañon, one hundred to two hundred feet deep. The course 
of the river is first northwest for twenty-five miles, then turning 
abruptly it flows southwest, and then south for about seventy-five 
miles. This valley has an average width of twelve miles. It is 
limited on the north and west by the Roan or Book Cliffs and 
their foot-hills, which follow the general course of the river. 
These cliffs rise from the valley in a succession of steps to a 
height of about four thousand feet above it, or eight thousand to 
eighty-five hundred above the sea. 
From its crest, this plateau (for the Book Cliffs are but the 
southern escarpment of a plateau) slopes to the north-northeast 
at an angle of not more than 5°. It extends from the Wahsatch 
Mountains on the west, to the foot-hills of the Park Range on 
the east, and presents everywhere the same characteristics. The 
Green River crosses it, flowing in a direction exactly the reverse of 
the dip. It borders the Grand on the north for one hundred and 
fifty miles, the crest forming the divide between the Grand and 
the White. On the south side of the crest are broken cliffs ; on 
the north side, the branches of the White River immediately 
form cajions. This leaves the divide in many places very narrow, 
in some cases not more than thirty to forty feet wide, with a 
vertical descent on the south towards the Grand River and an 
extremely steep earth slope (35° in many cases) at the heads of 
the streams flowing north to the White River. This crest, though 
not over eighty-five hundred feet in height, is the highest land 
for a long distance in every direction. 
After leaving the Uncompahgre agency, the party followed 
Gunnison’s Salt Lake road to the Grand and down that river to 
the mouth of the Dolores, in latitude 38° 50’, longitude 109° 16’. 
At this point they turned northward and went up to the crest of 
the Book plateau. They followed this crest to the eastward for 
upwards of a hundred miles to longitude 108° 15’, then descended 
tothe Grand and followed it up to longitude 107° 35’, and thence 
went, via the White River (Ute) Indian agency, to Rawlins, 
where they arrived on October 23d. 
The whole area worked is about thirty-five hundred square 
miles, in surveying which about sixty stations were made. The 
geological work of this division by Dr. Peale connects directly 
with that done by him in 1874 and 1875. Sedimentary forma- 
tions prevail in both districts visited during the past season. 
