394 N. H. DAETON — STRATIGRAPHY OF THE BLACK HILLS, ETC. 



Knowlton,* who have shown from the faunal, floral, and stratigraphic 

 evidence that they are of Laramie age. 



Bighorn Mountains 



general characteristics of the section and list of formations 



During the past three seasons many months have been devoted to a 

 study of the stratigraphy of a portion of the eastern side of the Bighorn 

 uplift. Some observations in this district were made several years ago 

 by Mr George H. Eldridge.f The Bighorn section presents much simi- 

 larity to that of the Black Hills, but with certain differences of detail, as 

 might be expected ; the Cambrian and Ordovician and also Graneros 

 are more extensively developed, the Red beds are thicker, the Lakota 

 and Dakota sandstone and Niobrara formations are much less distinct, 

 and the Greenhorn limestone was not recognized. The following is a 

 list of the formations on the east side of the Bighorn mountains in 

 Wyoming : 



Cretaceous. .. . 



Jurassic. .... 



Triassic (?) or 

 Permian. 



Carboniferous 



Ordovician. . . 

 Cambrian 



Algonkian or 

 Arehean. 



Formations. 



f Laramie . . 



Fox Hills. 



Pierre 



Niobrara. . 

 Benton . . . 



Cloverly. . -j 



Morrison. 

 Sundance . 



Ch ug water 



Ten sleep. 

 Amsden.. 



r 



I 



Little Horn. 

 Bighorn 



Dead wood. . . 



Principal characters. 



Sandstones and shales, with local coal 



beds ; lenses of conglomerate near base, 



Soft buff sandstone 



Dark gray shales 



Gray shales 



Dark shales : sandy shale, with thin 



rusty sandstone layers at base 



Gray to purple clay (Fuson) 



Coarse sandstone (Lakota) 



Massive shales and sandstones 



Buff sandstones and green shales 



Red sandstone and shales with gypsum 



(Spearfish). 

 Purple to gray limestone (Minnekahta?) 



Red shales (Opeche ?) 



White sandstone 



Red shales, white limestone, and cherty 



limestone. 



Limestones of light color 



Limestone, in greater part very hard 



and massive. 

 Sandstone, shale, conglomerate, and 



limestones. 

 Granite. 



Thick- 

 ness. 



* Bull. Geol. Soc. Am., vol. 8, pp. 127-156. 



f U. S. Geol. Survey Bull., no. 119, Washington, 18*J4. 



JBeet. 



2,000: 



200 

 2,700 



200: 



1,150 



30 



30 



150-250 



300 



1,200 



5 



30 



50-200 



300 



1,100 

 250 



1,000 



