STEATIGRAPHY. 19 
long, gentle, smooth grassy surfaces presented by dip slopes of various 
beds of the limestones and sandstones form a characteristic feature 
of the western slope of the Laramie Mountains from Laramie to Tie 
Siding. They are interrupted here and there by monuments of 
bright-red sandstone. In the vicinity of Gilmore Canyon these slopes 
are capped by the 2J-foot layer of limestone (No. 8 in section on p. 14) 
that lies between the two beds of monumental sandstones. It seems 
remarkable that a stratum so thin and of such soluble material as 
limestone should have controlled erosion to the extent here shown. 
The stratum which forms the wide lower slopes a mile north of Colores 
is the limestone (No. 10 in the Gilmore Can von section, p. 14) coining 
just beneath the lower monumental sandstone. This limestone is 
13 feet thick in the vicinity of Colores. 
Paleontology and age. — The limestones and calcareous sandstones 
of the Casper formation have yielded but few fossils, though sparse 
faunas are found here and there. From the 24-foot bed of lime- 
stone (No. 13, p. 14) in Gilmore Canyon only a single Spirifer camer- 
atus was obtained, but the 8-foot bed of limestone (No. 6, p. 14) 
yielded an abundant fauna of the following species determined by 
G. II. Girty: 
Derbya? sp. 
Aviculipecten oecidentalis. 
Aviculipecten 2 sp. 
Myalina permiana? 
Plcurophorus? sp. 
Schizodus sp. 
Schizodus ineekanus. 
Patellostium montfortianum. 
Eupliemus sp. 
Bellerophon crassus. 
Soleniscus hallanus? 
Murchisonia aff. M. terebra. 
Tainoceras occidentale. 
Nautilus sp. 
Orthoceras sp. 
Ammonoid indet. 
Doctor Girty regards these species, taken as a whole, as very 
closely related to and many of them probably identical with those 
from the upper part of the Pennsylvanian series in the Kansas section. 
From limestones in the middle of the formation on the slopes of 
Laramie Mountain 20 miles north of Laramie were obtained Pro- 
ductus semireticulatus, P. corn, Archaeocidaris sp., and Pinna sp. (deter- 
mined by Doctor Girty), all of Pennsylvanian age. In the upper lime- 
stone 2 miles east of Laramie Bellerophon sp. was found, and in the 
lowest limestone on the mountain slope 6 miles east of Laramie occur 
Meekella striaticostata, Spirifer cameratusf, and Bellerophon sp.* In 
the upper limestone a mile north of Satanka Orthotetes sp. occurs in 
abundance. In the lower limestones on Gilmore Canyon 8 miles 
southeast of Laramie Spirifer cameratus was obtained. 
Arnold Hague, of the Fortieth Parallel Survey, reported Pennsyl- 
vanian fossils from localities on Sybille Creek, Cheyenne Pass, and 
at a point 5 miles northwest of Sherman. The first locality was in 
a Hague, Arnold, and Emmons, S. F., U.S. Geol. Explor. lot li Par., vol. 2, Descriptive geology, 1*77, 
pp. 70-77. 
