CHA PT) By Velae 
WIND RIVER RANGE. 
The Wind River Range has a general course a little west of north 
and east of south of about 88 miles, and a breadth of from 12 to 32 miles. 
Within the present district there lies some 36 miles of the northern por- 
tion of the range, of which it forms by far the most prominent orographie 
feature. The southeast corner of the district lies in the heart of the 
mountains a few miles to the east of New Fork Peak; and thence the east 
boundary line descends north, gaining the Wind River Valley at the 
eastern foot at a point nearly due east of Union Peak, the most northerly 
eminence of the range. Circumstances beyond our control prevented 
the party penetrating the Alpine region, except at the northern ex- 
tremity of the range. But to the south, Mr. Wilson, the previous sea- 
son, succeeded in carrying the primary triangulation to the dominating 
summits at Fremont’s and, I believe, New Fork Peak, revisiting in com- 
pany with Dr. Hayden, at an earlier date the present season, the same 
region; so that the topographic features of the heart of the range, with 
its rock structure and interesting glacial phenomena within the district, 
have been subjects of investigation by several members of the survey. 
Our own work, however, was mainly confined to the flanks of the range, 
and chiefly within the belt occupied by the uplifted sedimentary forma- 
tions, the exhibition of which, as displayed in the gorges through which 
the streams descend on their way to the plains, is of extreme simplicity. 
Archean area.—The summit of the range within this district is com- 
posed of Archean rocks, forming a broad wedge-shaped area with the 
apex resting on Union Peak and expanding to the south-southeast, 
where along the forty-third parallel it may reach a maximum width of 
30 miles. The watershed and main topographic crest lies to the west 
of the central line of this area, forming a massive ridge to the south out 
of which erosion has sculptured the huge mountain summits dominating 
the range. The whole summit is lifted above timber-line between 2,000 
and 3,000 feet. To the north the summit widens into a plateau, its 
surface paved with weathered blocks of granite and rising here and 
there into broad-based domes or craggy ridges a few hundred feet in 
elevation. This is the character of the range from Union Peak south 
to near the line of 45° 15’. 
The eastern face of the main ridge, from a point opposite the sources 
of Torrey’s Creek, south at least as far as Little Wind River, breaks 
down precipitously, the stream sources draining this side of the range 
rising in elevated rugged basins and amphitheaters along the foot of 
the summit ridge. The united waters of these streams generally take 
a direct course transverse to the general direction of the range, and 
soon enters the broad belt of uplifted sedimentary formations reclining 
on the flank of the range, in crossing which they have eroded deep, 
picturesque cafions displaying the complete Paleozoic and the lower 
members of the Mesozoic series of formations. This belt of uplifted 
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