242 Prof. Hayden's Explorations. [April, 
north by the parallel of 39 0 30’, and included between the 
meridian of 108 0 and 109° 30'. 
This division took the field at Canon City, Colorado, 
about the middle of August. The party travelled nearly 
west up the Arkansas River, over Marshall’s Pass, and down 
the Tomichi and Gunnison Rivers to the Uncompahgra 
(Ute) Indian agency. Here they secured the services of 
several Indians as escort to the somewhat dangerous country 
which they were first to survey. This area, lying south of 
Sierra la Sal, was worked without difficulty. It is a broken 
plateau country, and presents many extremely curious pieces 
of topography. Eleven days were occupied in this work. 
The Grand River, from the mouth of the Gunnison River 
to that of the Dolores, i.e., for nearly a hundred miles, flows 
along the southern edge of a broad valley, much of the way 
being in a low canon, 100 to 200 feet deep. The course of 
the river is first north-west for 25 miles ; then turning ab- 
ruptly, it flows south-west, and then south, for about 75 miles. 
This valley has an average width of 12 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 4000 feet above it, or 8000 to 8500 feet 
above the sea. 
From its crest this plateau (for the Book Cliffs are but the 
southern escarpment of a plateau) slopes to the N.N.E. at 
an angle of not more than five degrees. 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 100 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 Canon immediately. This leaves 
the divide in many places very narrow, in some cases not 
more than 30 to 40 feet wide, with a vertical descent on the 
south toward the Grand River, and an extremely steep 
earth-slope (35 degrees in many cases) at the heads of the 
streams flowing north to the White River. This crest, 
though not over 8500 feet in height, is the highest land for 
a long distance in every direction. 
After leaving the Uncompahgre agency, the party fol- 
lowed Gunnison’s Salt Lake road to the Grand, and down 
that river to the mouth of the Dolores, in latitude 38° 50', 
longitude 109° 17'. At this point they turned northward, 
