PEALE.] GEOLOGY BEAR RIVER GROUP BITTER CREEK SERIES. 145 



Bear River group — Continued. 



Locality. 



Description of strata. 



Age. 



Authority. 



Eeference. 



Evanston coal 



Evanston . 



Referred p r ovis- 

 ionally to Eorfc 

 Union (C r e t a - 

 ceousjSTo. 6). 



Half Eoceuo and 

 half Miocene. 



Cope 



Lesquereux 



Do., p. 441. 



American Jojirnal 

 of Sciences and 

 Arts, vol. vii, 

 June, 1874. 



It seems to be pretty well established that the' lower portion of the 

 coal-beds at Coalville and Bear Eiver belong to the upper part of the 

 Cretaceous formation. In this place it is proper to refer to the Judith 

 Eiver beds which Dr. Hayden (Report for 1867-'68-'69, p. 56) placed 

 below the Fort Union group. Professor Meek (Report U. S. Geol. Sur- 

 vey for 1862, p. 460) says, "That the Judith River beds may be Creta- 

 ceous, I am, in the light of all now known of the geology of this great 

 internal region of the continent, rather inclined to believe." In an 

 article on some fossils from near the eastern base of the Rocky Mount- 

 ain's, Colorado (Bulletin U. S. Geol. and Geograph. Survey, second 

 series. No. 1, pp. 40, 41), he refers the Judith River beds to the upper part 

 of the Cretaceous. He says, " Whether they may," "in the Upper Missouri 

 country, be distinct enough from the Fox Hills group to form a sixth 

 subdivision of the Cretaceous series, holding a position just above the 

 latter, or whether they ought rather to be regarded as merely an upper 

 member of the Fox Hills group, may admit of some doubt in the present 

 state of our knowledge; though I strongly incliue to the latter opin- 

 ion. It is true, however, that they might really be properly distinct, as 

 a subdivision of the Cretaceous, from the Fox Hills group, and still be 

 so intimately related to the latter that some of their characteristic 

 species of fossils might range down into the same at the Colorado locali- 

 ties (just as some of the Fox Hills types also occur in the Fort Pierre 

 group below, at many localities), without necessarily proving that these 

 two subdivisions should not be treated as distinct rocks." 



Whether or not the coal strata at Evanston are equivalent to the 

 coal strata of Coalville cannot yet be positively stated. The considera- 

 tion of these beds belongs properly to the latter part of the preceding 

 chapter, but as their age was for some time a matter of doubt, I have 

 thought it best to take them up here. 



In the next table I present the beds of the Bitter Creek series. Dr. 

 Hayden has considered them Eocene or Transitional, Prof. E. D. Cope 

 called them Bitter Creek (Cretaceous), (Report U. S. Geol. Survey, 1873, 

 p. 435). 



Bitter Creeic series. 



Locality. 



Description of strata. 



Age. 



Authority. 



Eeference. 



Bitter Creek Valley 

 Hallville. 



Hallville, Black 



Dark clays, sand- 

 stones, slates, and 

 coal-heds. 



Lower Eocene or 

 Transitional, 

 from Cretaceous 

 to Tertiary, in 

 part, at least. 



Eocene or Tran- 

 sitional. 



Fossils Eocene 



Lower Miocene . . . 



Hayden 



....do 



Report IT. S. Geol. 

 Survey, 1870, pp. 

 75, 7G. 



Do., pp. 164,165; 



Do., p. 298. 



Report IJ. S. Geol. 



Buttes Station, and 

 Point of Rocks. 

 Hallville coal mines. . 







Medicine Bow 





Lesquereux. .. 







Survey, 1871, p. 306. 



10 H 



