256 TRANSACTIONS OF THE [may 18, 
out the southern part of the valley, wherever exposed, the Terti- 
aries are seen to be approximately horizontal and to be com- 
posed of soft friable beds. Along the north wall of the valley, 
however, there is a sharp break and the Tertiary rocks which 
come to the surface lie immediately against the quartzitic sand- 
stones of the plateau and dip to the south at an angle of 25°. 
They are of a rather coarse, gritty character, containing many 
pebbles, and are prevailingly calcareous. They are unlike any 
Tertiary in the region ; but from their calcareous nature, the fact 
of their being upturned at so high an angle, and their apparent 
connection with the series which sweeps around the eastern end 
of O-wi zu-kuts Plateau, they are assigned by Mr. Emmons to 
the Green River age. There seems to be a decided difference 
between the strata which are seen uptilted along the base of 
O-wi-zu-kuts Plateau and the soft, white, friable, horizontal beds 
of the valley itself, which are seen to extend eastward well to- 
wards the divide, separating the valley of Vermilion Creek 
from that of Little Snake River. It is notimprobable that there 
are two distinct members here—the Green River, which is seen 
inclined along the northern edge of the park, and a more recent 
horizontal member assigned to a special group by Powell and 
which overlies the beds we have referred to the Green River 
age. 
S. F. Emmons* classed the whole series as Green River shales, 
but he seems to be more uncertain than King as to their real 
geological horizon, for he says: “There is a possibility also 
that the upper beds of Brown’s Park, which have been colored 
as Green River Eocene on the map, may prove, on further in- 
vestigation, to be of Pliocene age.” 
He further states in a foot-note: ‘‘ Since the above was writ- 
ten it has been reported that fossils of a Pliocene type have 
been found in the Tertiary beds of Brown Park.” 
Charles A. White,} who has most recently studied this region, 
regarded the whole series as equivalent to the Uintah or latest 
Eocene beds which are exposed to the south of the mountains. 
He further colors the beds on the map accompanying his 
report as extending far to the southeast along the Yampah 
River. He has, however,advanced no facts to support his theory 
concerning their age and seems to be somewhat undecided in 
the matter. I will quote what he has to say on the subject :{ 
“The Tertiary strata of this district are divided into four 
groups. The three lower ones are usually referred to the Eocene 
=U; = Geological Exploration of the Fortieth Parallel. Vol. II., p. 205. 
+ U: er Geclorieal Exploration of Fortieth Parallel, Vol. II., page 224. 
~U. S. Geological Survey. Ninth Annual Report, page 690. 
