444 N. H. DARTOX PALEOZOIC AND MESOZOIC OF WYOMING 



lying on a small amount of light colored shale of the usual character. 

 Sovxtheast of Eml^ar this sandstone also predominates, merging downward 

 into thin-bedded gray sandstones and more or less shale, which weathers 

 to a buff color. In a small outcrop on east side of Bighorn river, just 

 above the mouth of the canyon, the rock is mostly gray sandstone, but a 

 thin bed of limestone is included. In extensive exposures on the east side 

 of Eed creek, 3 miles east of the summit of Black mountain, the forma- 

 tion is about 150 feet thick. At the top are soft, massive sandstones, 

 mainly of buff color, but partly pink, lying on reddish and maroon clays. 

 In the middle are 50 feet of red, sandy clays, with a few soft sandstone 

 laj-ers from 6 inches to a foot thick and some layers of purple clay. The 

 lower 50 feet are massive, sandy clays of gray and dirty maroon tints in 

 alternating bands lying on Sundance sandstone without evidence of struc- 

 tural discordance. 



Casper-Douglas-Medicine Bow region. — The Morrison formation ap- 

 pears extensivelj^ in the slopes of the ridges of Cloverly sandstone from 

 Poison Spider creek to head of Bates creek, about Alcova, south of Big 

 Muddy station and Douglas, in the Haystack range, Freezeout and Shir- 

 ley hills, in the uplifts north and east of Medicine Bow, and the long 

 monocline on the east side of Little Medicine creek. In the east end of 

 the Freezeout hills and in the Como ridge, 6 miles east of Medicine Bow, 

 are the famous collecting grounds of dinosaur remains. The thickness 

 varies from 200 to 300 feet. The material is the typical light colored, 

 massive clay or mixture of fine sand and clay, with sandstone layers and 

 occasional thin limestone beds. The claj^ is mostly pale greenish gray, 

 but in all exposures portions are maroon and buff. Near Freeland the 

 middle beds are distinctly red. In the vicinity of Alcova and southward 

 there is a massive light colored sandstone at the base suggestive of the 

 Unkpapa sandstone of the Black hills. It is 40 feet thick at the south 

 end of Platte canyon 35 miles above Alcova. At this place and eastward 

 nearly to Difficulty the thickness of the formation is 325 feet. The fol- 

 lowing section near Dyer's ranch by TV. IST. Logan^" illustrates the prin- 

 cipal features in the eastern end of the Freezeout hills, where, however, 

 tlie stratigraphic limits are somewhat uncertain : 



Section of Morrison Formation in Freezeout Hills, Wyoming 

 No. Feet 



24. Grayish white sandstone (may be basal Cloverly) 50 



23. Drab clay with dinosaur remains 70 



22. Brown to bluish gray, sandy limestone with molluscan 



fossils 1 



"Ibid., pp. 113-115. 



