254 STANTON 



Pepperberg and Barnett collected the plants listed by Knowlton is in 

 the highest rocks exposed in this syncline and may belong to the typical 

 Fort Union. At any rate it is higher than any of the dinosaurs of 

 the Triceratops fauna which are reported to be common in the sand- 

 stones immediately overlying the marine shale throughout this area. 

 The " Ceratops beds" of this section are apparently directly connected 

 on the northwest with the similar formation tentatively referred to 

 the Laramie (?) which underlies the coal-bearing Fort Union of the 

 Bull Mountains field, while on the south they follow approximately 

 parallel with and usually east of the Chicago, Burlington, and Quincy 

 Railroad to a connection with the lower part of the Piney formation 

 in the Sheridan, Wyoming, area east of the Bighorn Mountains. 

 Throughout these areas the most prominent feature of the formation 

 consists of the exposures of light-gray, rather soft sandstones. 



Bull Mountains, Montana. — A preliminary account of part of this 

 area with a description of the coal-bearing portion of the section has 

 been published by L. H. Woolsey.^ He says of the Fort Union for- 

 mation : 



it is composed chiefly of gray to buff sandstone alternating with gray 

 shale. The sandstone, though extremely variable, is commonly 

 massive and evenly distributed throughout the section. The base 

 of the formation is strongly marked by contrast with a band of olive- 

 green clay shale, which belongs to the next lower formation. This 

 shale is well exposed along the Billings — Roundup road, 2 or 3 miles 

 south of Buckey post-office, and may be traced westward across vari- 

 ous branches of Razor Creek, through Pratt's ranch, and down Dean 

 Creek to Musselshell River. 



In Woolsey's columnar section,^* under the term ''Beds on Dean 

 Creek," it is represented as about 200 feet thick and as resting on 

 the "Laramie" sandstones. The top of this shale is marked by the 

 apparently eroded surface mentioned on p. 63. It has yielded a 

 considerable number of fossil plants which Doctor Knowlton has 

 referred to the Fort Union as follows: 



Plalanus hasilohata Ward 

 Plalanus guillclmoe Gopp. 

 Platanus raynoldsii Newb. 



•"Bull U. S. Geol. Survey, No. 341, 1908, pp 60-75 

 «0p. cit., PI. IV. 



