428 T. B. Comstock— Geology of Western Wyoming. 
and overlie conformably a thick deposit of sandstones and arena- 
ceous rocks, which, though varying sufficiently to admit of 
division into minor groups, are best considered here under the 
comprehensive name of Kocene. Careful notes and collections 
rocks are passed over before reaching the main divide or axis 
of the range, beyond which the original structure is very largely 
obliterated by various kinds of erosion, and the filling in of the 
gravels and finer material of the drift. In the metamorphic 
Delight, beyond Camp Stambaugh. The gold of this region 
occurs in thick veins of impure quartz, associated with consid- 
erable silver, and more or less of iron pyrites. The greater por- 
tion is disseminated through the vein rock, but it not unfre- 
quently is found native in cavities in the quartz, in fair sized 
nuggets. 
From Camp Stambaugh the route lay northwest along the 
eastern base of the Wind River Mountains, as far as Ca 
Brown on the Little Wind River, thence across the Wind River 
Valley, over the Owl Creek Mountains, and across the valley of 
Owl Creek above the janction of its forks. 
The geology of the eastern slope of the Wind River Moun- 
tains is quite simple, affording many fine sections exposing 
representatives of all of the great groups of sedimentary rocks, 
from the Silurian to the Cretaceous inclusive, conformable to 
each other, and dipping away from the underlying metamorphi¢ 
rocks at an angle of 20°. On one of my trips into these mour 
tains I discovered limestone strata of Silurian age, cn 
remains of Trilobites and Corals not yet tpg = bees 
for the present I refer to the Potsdam Period. e abe 8 
strata are best represented by the Oriskany sandstone, ser 
Ing quite abundant remains of Spirifer arenosus. The pert 
longing to the Carboniferous age would seem to be & 
wholly Subcarboniferous, containing Orthis Michelin, pi 
tion Canadense, a Chonetes, and a species of Poteriocrinus 7, Ot af 
fossils collected, but undetermined, may prove the existence 
later Carboniferous strata, however. uae 
_ Aproblem of no little difficulty is the definition of the lines - 
junction of the Triassic with the Jurassic, and the Jurassi¢ a 
