Cheyenne Sandstone of Kansas. — Oragin. 31 
great abruptness, and offering, at the southern end, the following 
section : 
BLUFF CREEK SECTION. 
No. 
Al'l'ROX. 
Thicknkss 
IN FEET. 
Description. 
1 
Lake Marl slope. 
2 
50 
Loup Fork calcareous concretionary grit, with remains of 
Mastodon, Aphelops, Hipparion, etc. 


±0 
Neocoinian shales, light olive brown to yellowish gray in the 
upper third of its thickness (which is also more or less arena- 
ceous), becoming gradually bluish or dark slate-colored below. 
Fossils mostly of the commoner Neocomian sorts— not separated 
into faunal horizons. 
1 
8-10 
Soiled grayish brown sandstone, of soft earthy texture. with 
slight admixture of dark earth or shale. Xo fossils observed. 
5 
75—00 
Dark ( olive-brown to blue-black) Neocoinian shales, nearly 
barren of recognizable fossils, and based on the Triassic Red- 
beds. 
A portion of Xo. 4 of the Bluff Creek section, at the lower end 
of the " amphitheatre. ! ' is cut off from the main stratum and 
stands as a rapidly-wasting pinnacle. This, and certain features 
of the outcrop of the stratum in the bluff itself, remind one of the 
Cheyenne Sandstone, and the occurrence of such a stratum so far 
above the base of the series indicates a partial return to the 
physico-geographie conditions under which the Cheyenne sand 
stone was formed. 
At a point a few miles below the "amphitheatre'' on Bluff 
creek, and about a mile above the entrance of Hackberry creek, 
the base of the Cretaceous is marked by a shell-lied which has 
close lithological resemblance to No. 5 of the Belvidere section. 
but is more or less colored by material incorporated from the Red- 
beds. The prevailing fossils in this shell-bed are Trigonia emoryi 
and Ostrea diluviana, the stratum being a breccia chiefly of the 
former shell, with an arenaceous matrix, and occasional specimens 
of Exogyra flabellata. Tdonearca vulgaris, etc. Fifty to seven- 
ty-five feet above this shell-bed and separated from it by a 
slope, there outcrops a second arenaceous gray shell-rock. 
in which the fossils arc very obscure, but whose lit h< >- 
logic resemblance to Belvidere •"> is perfect, and which yields 
the large sigmoid worm-burrow of the latter. Its horizon 
is apparently close to that of the unfossiliferous stratum 
of earthy sandstone seen in the Bluff creek "amphitheatre I No. 
4 of section). 
