264 REPORT UNITED STATES GEOLOGICAL SURVEY. 
depressions already existing, down which they slowly moved bearing 
and pushing along their burden of detrital materials, which were un- 
loaded and built into the huge morainal ridges filling lateral depressions 
along the mountain course of the glacier and piled up on the surface in 
the edge cf the plain. These occurrences furnish the most legible evi- 
dence of the magnitude of the individual glaciers descending along the 
eastern flank of the Wind River Range, which in some instances ex- 
tended beyond the mountain foot 2 distance of several miles out into the 
basin. E 
While denuding agencies of one kind or other have wrought with 
startling cfects, carving out stupendous mountain forms and broad 
valley depressions, the phenomena resulting from these actions, as seen 
to-day in the region of the sources of Wind liver, present comparatively 
small evidence of glacial origin. This may be attributable to the soft 
nature of the geological formations in that region, but the glacial de- 
posits which were here found are much less conspicuous than these met 
with along the foot of the Wind River Mountains. However, the oceur- 
vences along the upper course of Wind River present the same evidence 
of the local extent of the glaciers as those met in the mountain borders 
to the south. The erratic materials along the stream as far down as 
Warm-Spring Creek may be traced to the conglomerate and great vol- 
canic conglomerate and lava formations, that encircle the head of the 
valley. The materials consist almost exclusively of the various sorts of 
voleanic rocks, basalt and trachytic lavas, found tn sitw in the meuntain 
summit about Togwotee Pass. They have been distributed by trans- 
porting agents as far down the valley as North Tork, at least, though 
below the confluence of Warm-Spring Creek they are mingled with 
other kinds of rock débris derived from the Wind River Mountains, 
becoming less and less conspicuous and finally disappearing as a com- 
ponent of the superficial detrital deposits along the stream. 
Above Du Noir Creek, the upland benches a few miles north of Wind 
River are sparsely covered with water-worn erratics consisting chiefly 
of voleanic rocks, and sparingly of fragments of reddish-white lami- 
nated quartzite and dark drab limestone resembling ledges occurring in 
Carboniferous and Jurassic horizons, and which evidently were brought 
down from the mountains lying to the north. But for the most part 
these upland slopes are covered with light sandy soil derived from the 
disintegration of the subjacent soft arenaceous Tertiary deposits. Above 
Du Noir Creek the uplands are more thickly strewn with water-worn 
volcanic bowlders which embrace all the varieties of these rocks occur- 
ring in the watershed around Togwotee Pass, the deposit having much 
the appearance of morainic origin. The wide intervale at the conflu- 
ence of Du Noir and Wind River is paved with these erraties. 
Just below in the neighborhood of Warm-Spring Creek, glacial phe- 
nomena, So far as they are dependent on morainal deposits for their recog- 
nition, are perhaps not of the most conclusive character. The mountain 
side at an elevation of 600 feet above the valley is strewn with unevenly 
dispersed accumulations of probable glacial origin. ‘The loose materials 
consist of a variety of metamorphic rocks such as occur in the interior 
portion of the range, together with limestone fragments from the outer 
flank of the mountain. But lower on the slopes or in the benches bor- 
dering the basin, these abraded erratics are spread out in well-defined 
terraces where they have been transformed into a sort of conglomerate 
by calcareous infiltrations from springs, with which are associated a 
variety of interesting phenomena. 
It is difficult to decide the relations of the bowlder deposits in the 
