I 



Douglass : A Geological Reconnaissance, 277 



The Fox Hills (?) 



Conditions are such that the upper continuation of the Bearpaw 

 shales is not usually well exposed in the Fish Creek section. On Mr. 

 B. Forsythe's ranch, on a branch of Big Coulee Creek, and in the 

 bluffs northeast of Columbus they can be studied to advantage. The 

 dark shales become more arenaceous, at least there are more layers of 

 sandstone. Near Columbus these beds contain some brown concre- 

 tions in which are marine fossils. I do not know that these have been 

 specifically determined, but am inclined to think that they are Fox 

 Hill species. In the two localities above mentioned the dark shales 

 and shaly sandstones end rather abruptly and are overlaid, perhaps 

 unconformably, by heavy gray sandstones. Near McClatchy's house 

 on Fish Creek a few fossil mollusca were found in the sandstones. 



Laramie and Doubtful Laramie. 



Fish Creek Section. — The thick series of strata between the gray 

 sandstones, just referred provisionally to the Fox Hills, and the Fort 

 Union beds, may be divided temporarily, for convenience of descrip- 

 tion, into five lithological divisions. The total thickness must be sev- 

 eral thousands of feet. 



A. Dark shales, sandy shales, and sandstones, sometimes weathering 

 into something like bad-land forms. They contain in almost every 

 good exposure bones of dinosaurs, such as Triceratops and probably 

 Tracliodon. They are well exposed («) northwest of the McClatchy 

 house on Fish Creek, (/;) south of the Lake Basin, and (r) north of 

 Columbus, on the road from Columbus to the Lake Basin. 



B. Sandstones and some shale. The sandstones, at least in part, 

 are dark, sometimes iron-stained, and occur in rather thin layers. In 

 places they are gray. A and B and the doubtful Fox Hills might be 

 united. 



The Fox Hill sandstones, and A and B of the Laramie, form a prom- 

 inent ridge, which can be traced southeastward from near the American 

 Fork, south of Harlowton, a distance of sixty miles or more into the 

 southern part of Yellowstone County, where it forms the southern rim 

 of the Lake Basin. The beds composing the ridge dip strongly to the 

 southward in the more western portion near the mountains, but in the 

 region north of Columbus they are more nearly horizontal, dipping 

 slightly to the south. 



C. Rather soft gray sandstones alternating with various colored 



