RESUME — UPPER CARBONIFEROUS AND RED BEDS 437 



but the precise relations of these deposits to the Red beds of Colorado 

 are not determined. In 1901 I found a fragment of a shoulder bone at 

 the Red rocks in Purgatoire canyon in southern Colorado which Pro- 

 fessor F. A. Lucas regarded as a portion of a Bolodont, an opinion which 

 was sustained by Dr E. Fraas, and this genus is considered typical of 

 the Triassic. The lower Red beds of the Rocky Mountain front range, 

 which have yielded no fossils, undoubtedly merge into Upper Carbonif- 

 erous limestones both to the north and south, and they can be correlated 

 also with formations in the Bighorn mountains and Black hills. The 

 suggestion that the lower Wyoming in Colorado is of Upper Carbonif- 

 erous age was first made by S. F. Emmons in the monograph on the 

 Denver basin.* According to G. I. Adams, the Red beds of south-central 

 Kansas and southward merge into the limestone and shales of the Permo- 

 Carboniferous series, and the evidence of this relation appears to be 

 entirely satisfactory. It is certain that the Red beds represent a con- 

 siderable interval of time, and the discover}' of fossils at one horizon 

 does not settle the age of the whole series. 



Throughout the Black hills, Bighorn mountains, and much of the 

 region south, the Upper Carboniferous and Red Bed series presents a gen- 

 eral succession, as follows, beginning at the top : A thick mass of gyp- 

 siferous, red, sandy shales; thin mass of thin bedded limestone; thin 

 mass of red, sandy shales; thick, hard, light-colored sandstone, and at 

 base, limestones and sandstones giving place to sandstones and con- 

 glomerates, the basal series lying unconformably on Mississippian lime- 

 stones, on Cambrian or on old granites and schists. The columnar sec- 

 tions in plate 35 illustrate some of the principal features. 



In the Bighorn and Black Hills uplift the assignment of formations 

 to the Upper Carboniferous or Pennsylvanian is somewhat provisional. 

 A few fragmentary fossils were observed, but they were hardly deter- 

 minative. The Minnelusa formation, which succeeds the Pahasapa 

 (Lower Carboniferous), is a strongly marked series, supposed to be Penn- 

 sylvanian, in part at least, from a few fossils which I obtained in its 

 upper beds near Hot Springs. These fossils were Productus semireticu- 

 latus and Seminula subtilita(f). In the slopes of the Bighorn mountains 

 there is a series somewhat similar to the Minnelusa beds, which I have 

 designated the Amsden formation and Tensleep sandstone. The former 

 contain a basal red shale member suggesting the thin one which occurs 

 at the base of the Minnelusa formation of the Black hills, and alternations 

 of limestone and sandstone with much chert, which suggests the lower 

 two-thirds of the Minnelusa formation, but with purer limestone deposits. 

 These limestones have so far yielded only some fragmentary, indetermi- 



* Loc. cit., p. 19. 



