224 REPORT UNITED STATES GEOLOGICAL SURVEY. 
ness of 10 inches and upwards each ; several of the thinner seams sepa- 
rated by thin partings of clay might be mined as one bed, many of them 
showing an aggregate thickness of 20 to 30 inches of coal. Commi- 
nuted vegetable remains occur throughout, and at. one carbonaceous 
horizon in the middle portion of the series a few imperfectly preserved 
fossils were found belonging to the genera Unio, Hydrobia?, Spherium, 
which Dr. White provisionally refers to Bear River Laramie forms. In 
nearly horizontal sandstones in the upper part of the ‘section examined 
by Mr. Perry a species of Viviparus closely allied to, if not identical 
with, V. paludineformis Hall, was obtained, which, according to Dr. 
White, indicates the Wahsatch age of the supralignitic horizons. 
The latter deposits, on the before-mentioned northeast fork of Gros 
Ventre River, continue for a distance of 1$ to 2 miles; the exact 
thickness attained by them is difficult to determine. The upper por- 
tion may be destitute of coal deposits, although presenting great uni- 
formity in composition and lithologic characters. Overlooking a more 
or less extended belt of the outcrops of this series, it presents a light 
buff color that readily distinguishes it from the brownish inferior con- 
glomerate, as also from the overlying series. But it would be prem- 
ature at this time to attempt to draw the line of demarkation between 
the lignite-bearing inferior portion with its supposed Laramie inverte- 
brate fauna and the apparently conformable upper portion character- 
ized by the Viviparus paludineformis (2), except arbitrarily; while the 
non-conformity between the basis conglomerate and the subjacent Cre- 
taceous deposits is unmistakable. 
The above horizon is succeeded to the east by a series of variegated 
pale red or pinkish clays (No. 15), in apparently conformable superposi- 
tion, and inclined gently northeastward. The outcrop of this member 
is traced as a somewhat narrower belt, distinguishable by its peculiar 
color at long distances. It frequently appears in bluffs and denuded 
slopes, in which respect, as also the banded disposition of the coloring 
matter, pink and light drab, forcibly recalls the peculiar deposits so 
prominently developed in the Wind River Valley, east of the present 
basin. To the south these deposits are not so distinctly traced, so that 
at present it would be impossible to define their areal extent in that 
quarter. In the opposite direction, however, they are seen to rise up in 
the broken slopes culminating in the Mount Leidy highlands on the 
north border of the basin, beyond which again they were not with cer- 
tainty recognized. 
A considetably thicker series of very light drab and buff deposits, 
probably arenaceous clays and soft sandstone, including pale, orange- 
colored horizons (No. 16), overlies the last preceding deposits, rising up 
into and forming the bulk of the sedimentary deposits in the crest of 
the watershed separating this basin from the upper valley of Wind 
River on the east. They are but slightly disturbed from their original 
horizontal position, as appears from such exposures occurring along the 
streams descending either slope of the watershed. About midway be- 
tween Union and Togwotee passes, where the watershed is most de- 
pressed, 9,800 feet altitude, these deposits are clearly continuous with 
those occurring on the headwaters of Wind River. This region is gen- 
erally well wooded, and but for the barred bluffs along the drainage 
channels intersecting the watershed, its geological structure might not 
be so easily made out in the course of a hasty examination. No fossils 
were found in these deposits by which they might be compared with 
elsewhere well-determined Tertiary formations. 
To the south they are hidden beneath Quaternary débris ov er exten- 
