MOOE, STUDY OF THE MORRISON FORMATION 



83 



of the Chugwater- Sundance ridge on the one hand and the hog-back of 

 the Cloverly on the other. 



The formation is mostly made up of hard clay or massive shale, vary- 

 ing in color from pale greenish to maroon, with darker clay at its summit. 

 Several beds of light gray sandstone 2 to 30 feet thick are usually in- 

 cluded. "These sandstones are usually soft, and on weathering exhibit 

 thin, irregular bedding planes which generally have a peculiar wavy sur- 

 face suggestive of incipient cross-bedding." There is apparently a con- 

 formable contact between the Morrison and Sundance beds. In the first 



Fig. 38. — Section of the Morrison forma- 

 tion on South Fork of Rock Greek, 

 northwest of Buffalo, Wyoming. 



Scale, 125 feet to 1 inch. (Darton.) 



Fig. 30. — Section of the Morrison forma- 

 tion on the south side of Muddy Greek, 

 southwest of Buffalo, Wyoming. 



Scale, 125 feet to 1 inch. (Darton.) 



hollow south of South Fork of Eock Creek, northwest of Buffalo, the base 

 of the Morrison consists of 40 feet of soft greenish-gray and pale-buif 

 sandstones; then 80 feet of clays, 15 feet of the typical sandstone above 

 described, and at the top 30 feet of clays, maroon, bufi: and greenish 

 below and dark above. A mile south of Muddy Creek, southwest of 

 Buffalo, there is an exceptionally good outcrop of the Morrison formation. 

 It exhibits at the top 10 feet of reddish shale which grades down into 

 dark shale, followed by 240 feet of hard, chalky clays~ of maroon and 

 green color. This series of clays contains occasional thin sandstone part- 

 ings, and one bed 6 feet thick near the middle. This bed is hard, light- 

 colored, and weathers in thin beds with irregular wavy surface. Near 

 the base of the series the clay is red. Next below is an 8-foot bed of 

 Avhite sandstone. Below this sandstone and resting on the Sundance beds 

 are a few feet of soft gray and buff sandstones. On Little Poison Creek 



