Stevenson.] 400 [June 18, 



Inoceramiis, Unio, Cardium, Gyrena, etc 48 ft. 



16. Coal 5^ ft. 



17. Concealed 60 ft. 



18. Massive sandstone 220 ft. 



19. Sandstone and sandy clay with 0. soleniscus 14 ft. 



20. Sandstones and clays, not fully exposed 775 ft. 



21. Gray sandstone, with Inoceramus, Cardium, Ostrea, 



etc 30 ft. 



22. Sandstones and clays, with fragments of Ostrea 191 ft. 



23. Concealed 380 ft. 



24. Conglomerate, more or less coarse 860 ft. 



25. Great Echo Canon Conglomerate, more than 700 ft. 



Mr. Meek is inclined to regard this whole section below No. 25, as not 

 only Cretaceous but as belonging to the Middle Cretaceous, not higher 

 than No. 3. This conclusion appears to be quite improbable. This, it 

 is true, lies very near the western shore-line of the Cretaceous sea, for 

 no rocks belonging to that system have been found west from the 

 Wasatch Movintains at this latitude, which explains sufficiently the 

 coarseness of the sediments toward the base of the section. It certainly 

 seems proper that all above No. 6 should be placed in the Upper Cre- 

 taceous, for the fauna approximates the fauna of that horizon. The 

 succession of the rocks below No. 6 fully favors this view. 



Mr. Emmons, who has studied this region elaborately, maintains that 

 the Coalville and Bear River areas are but fragments of the great lignite 

 series seen further east, and that they are the western portions of the 

 Bitter Creek Group. That the Coalville section above No. 6, is equiva- 

 lent to the Bitter Creek Group, and therefore to the Fort Union Group, is 

 rendered very jjrobable when we consider the enormous thickening of the 

 rocks, shown alike by both sections, the general lithological resemblance, 

 and the presence of the fucoid, hitherto unknown below that horizon. 

 Of Mr. Emmons' work nothing has been published, except a brief resum§ 

 in Volvime III, of Mr. Clarence King's reports. Mr. Lesquereux regards 

 the two groups as iDractically equivalent. 



Retvirning now to the east face of the mountain, we reach the Colorado 

 and New Mexico portion of the area, about twenty miles south from 

 Cheyenne. In Colorado and eastern New Mexico, the Lignitic Group 

 shows the following section: 



1. Sandstones, yellowish, ferruginous, more or less conglomerate. 



2. Sandstones, shales, and coal-beds. The sandstones, gray to light- 



yellow. 



3. Sandstone, rusty-red to yellow, brown, and gray, containing thin 



coals, more or less concretionary, and passing downward into 

 a mass of clays and argillaceous sandstones. 



In many localities the clays and argillaceous sandstones seem to be 

 almost absent, but where the section is complete, as at Caiion City and 



