J. B. Hatcher — Ceratops Beds of Wyoming. 139 



the northwest at an angle of 16°. The exposure is a continu- 

 ous one, and commencing from below, the section is as fol- 

 lows : 



At the base are the Ft. Pierre shales of unknown thickness, 

 several hundred feet of which are exposed. They consist of 

 argillaceous, finely laminated, dark shales, quite soft and easily 

 eroded. They contain many limestone concretions and numer- 

 ous invertebrates; among others are Baculites ovatus, B. com- 

 pressus, Scaphites nodosus, Placenticeras placenta, Nautilus 

 Dekayi, etc. 



Overlying the Ft. Pierre deposits is an alternating series of 

 sandstones and shales with an estimated thickness of 500 feet. 

 In the lower portion of this series, the shales predominate, but 

 toward the middle the sandstones are in excess, and in the 

 upper 50 feet they entirely replace the shales. The sandstones 

 are of a yellowish brown color, very line grained, firm, and 

 well stratified below, but softer, and quite massive at the top, 

 where they contain numerous large concretions and a rich 

 marine invertebrate fauna. Representatives of this fauna 

 have been sent to Mr.' T. W. Stanton of the U. S. National 

 Museum, and were pronounced by him to be characteristic of 

 the uppermost Fox Hills in direct conformity with their strati- 

 graphical position. 



The Ceratops Beds. — Next come the Ceratops beds with 

 an estimated thickness of 3,000 feet, resting directly upon the 

 Fox Hills series. Immediately above the Fox Hills is a very 

 thin, but quite persistent, layer of hard sandstone, well strati- 

 lied, and quite cleavable along the lines of stratification. This 

 stratum of sandstone is about six inches thick, and is regarded 

 as the dividing line between the marine and fresh-water beds. 

 It is overlaid by about 150 feet of yellowish brown, well- 

 stratified sandstones apparently non-fossiliferons. These are in 

 turn overlaid by about 250 feet of almost white, fine-grained, 

 massive sandstones with numerous concretions, but no fossils 

 were found in them. Next comes the fossiliferous portion of 

 the Ceratops beds, consisting, as before stated, of alternating 

 sandstones, shales, and lignites. 



All the beds of the entire section are conformable, and bear 

 evidence of a continuous deposition, from the Ft. Pierre shales 

 up through the Fox Hills sandstones and the overlying fresh- 

 water Ceratops beds. The Ft. Pierre shales are not suddenly 

 replaced by the Fox Hills sandstones, but the transition is a 

 gradual one, and it is impossible to say just where the one ends 

 and the other commences. The same is true of the beds over- 

 lying the Fox Hills. The thin seam of hard sandstone, just 

 referred to as separating the fossil-bearing Fox Hills sand- 

 stones below from the very similar non-fossiliferous sandstones 



