28 LARAMIE BASIN, WYOMING. 
2 miles along the east slope of the Jelm Valley just east of Jelm. 
A small area is faulted to the surface just east of Sheep Mountain, 
3 miles north of Woods Landing. Some of the most extensive expo- 
sures are west and southwest of Red Buttes, at Red Mountain, west 
of Downey Lakes, on the east side of Centennial Valley, along the 
north face of Como Ridge east of Medicine Bow, along Little Medicine 
Bow Creek near latitude 42°, and in the ridge of which Bootheel Butte 
is one of the summits. There are large exposures in the Freezeout 
Hills, of which only the eastern margin extends into the area treated 
in this report. In the southern half of the Laramie Basin the Mor- 
rison lies upon the Chugwater red beds, but to the north the Sundance 
formation intervenes. 
Character. — The Morrison deposits are mainly hard clay or massive 
shale varying in color from pale greenish to maroon and having a 
peculiar chalky appearance. The prevailing tint is pale olive green. 
Thin beds of drab limestone and a few beds of light-colored sandstone 
are included. At some places there occur also concretionary masses, 
2 inches or less in thickness, of olive-green to dark-green brittle 
siliceous rock. A section of the formation in Como Ridge is as follows : 
Section of Morrison formation in Como Ridge east of Medicine Bono, Wyo. 
White, massive sandstone, conglomeratic (Cloverly). Feet. 
Bluish to greenish shales 50 
Limestone, lumpy 1 
Bluish to olive-green shales 30 
Limestone, lumpy 1 
Blue and red shale 120 
202 
In Red Mountain the formation is 128 feet thick and consists 
mainly of pale bluish shale which in the upper beds contains green 
nodular masses. At 36 feet above the base there is a 2-foot layer 
of limestone, and at 88 feet above the base a 1-foot limestone layer 
containing fresh- water fossils. At the base of the formation lies a 
series of light-colored sandstones and terra-cotta and bluish shales 
which may possibly represent the marine Jurassic, but, as they contain 
no fossils, they have been provisionally placed in the Chugwater. 
Section of Morrison formation on east slope of ridge west of Downey Lakes, Wyoming. 
Coarse sandstones and shales (Cloverly). Feet. 
Drab to olive-green shale 30 
Soft, coarse-grained, disintegrated sandstone with calcareous matrix 
containing teeth and bones 6 
Drab to blue shales 15 
Nodular limestone 1-2 
Blue shales 50 
Limestone 2 
Concealed; probably blue shale 30+ 
135+ 
