ST JOHN.] SURFACE FEATURES HOBACK-GREEN RIVER BASIN. 203 
ern border of the basin, similar Tertiary deposits were also met with 
which appear to have been little if at all disturbed from their nornal 
position. Along the Gros Ventre side of the basin perhaps the same 
observations, in part, hold good, with, however, certain exceptions in the 
neighborhood of the convergence of the Hoback Cafion ridge where the 
inclination of presumably Cenozoic strata is towards the mountain. The 
facts, therefore, imply dynamical movements within the area of the Wyo- 
ming Range and along the western border of the basin durmg a time 
subsequent to the deposition of the Tertiaries of the basin area; and 
was the tendency of these movements a downward one within the basin 
area and an upward one in the western mountain border, the subsidence 
in the one place would encroach on the former drainage planes and orig- 
inate a new system tributary to that of the depressed area. In this 
manner might have originated the Hoback, and at a time relatively re- 
cent compared with the inception of the Green River drainage. The 
extent of the movements above alluded to cannot at present be defined ; 
the appearances, however, indicate for them rather a local character, 
centering in the region of convergence of the Wyoming-Snake, Téton, 
and Gros Ventre ranges. 
The area embraced in the Hoback drainage is diversified by intervale- 
bordered streams and terraces, covered with herbage, aspen and ever- 
green groves; the open slopes, of course, are well sprinkled with the 
ubiquitous sage. Hemmed to the north and west by mountain ridges 
built up of variously color-contrasted rocks, it is an interesting and 
beautiful region. Approaching the mountains on the west and north, 
the benches ; gradually rise, the streams occupying deep valleys, and of. 
ten confined to narrows walled by steep blutts, the lateral drainage fur- 
rowing the high benches with narrow ravines separated by sharp ‘rid ges 
or steep slopes, broken by landslides into step-like inequalities, having 
the semblance of rude terraces. 
The almost equally extensive area belonging to Green River drainage, 
to the south, contains a greater proportionate extent of level bottom 
land immediately adjacent the stream, with broad belts of low, undulat- 
ing uplands on either hand; to the west, rising into the low water-di- 
vide, heading the basin sources of the Hoback, and to the east soon 
merging into the foot hills and morainal ridges Lyi ing at the western base 
of the Wind River Range. To the north “this portion of the basin is 
more broken, the tributary drainage which here reaches around the east- 
ern extremity of the Gros Ventre Mountains draining a small portion of 
their northern slope, having fashioned a few broad-topped spurs reach- 
ing from that mountain axis, with gradually diminishing elevation, far 
out into the valley. While still farther to the north, a broad, undulat- 
ing saddle-ridge, at least 15 miles in east-west length, stretches across 
from the northern slopes of the Gros Ventre Mountains to the west flank 
of the Wind River Range, forming the water-divide separating the 
Green from the Gros Ventre River. “The divide is about 9,000 feet in 
actual altitude, comprising a beautiful park-like region of open, grassy 
prairies, dotted with aspen thickets and more or less extensive tracts of 
evergreen forests. The Green, after holding a nearly north-south course 
of 26 miles within the limits of this district, here sharply bends upon 
itself, and a few miles above, to the southeast, emerges from its mount- 
ain course through one of the grandest gorges penetrating this side of 
the Wind River Range. 
This basin area is almost exclusively occupied by Tertiary deposits 
belonging to and continuous with the great Green River series of that 
age. The low water-divide separating the Green from Hoback’s River, 
