74 THE PERMO-CARBONIFEROUS RED BEDS OF 



In further remarks in the same paper Girty suggests the possibiUty that 

 the beds under discusion, together with many other beds in the western part 

 of the United States, may be found to be Gschehan in age. 



Girty ^ regards the invertebrate collected by Darton in Gilmore Canyon 

 (270 feet above the 24 feet of limestone in the Casper) "as very closely 

 related to that of the upper part of the Pennsylvanian division in the Kansas 

 section." 



The Forelle limestone and Satanka sandstone above the Casper south 

 of Laramie are in part gypsiferous. It was in the former that Knight's 

 fossils were found .'' According to Girty, the fauna is "late Pennsylvanian 

 or possibly equivalent to the Wreford limestone in the so-called Permian of 

 Kansas. ' ' These two beds are separated from the Chugwater by the Carbonif- 

 erous character of the fauna, "otherwise it might be regarded as a portion 

 of the Chugwater formation from near Laramie and Red Buttes. The 

 stratigraphic succession is strongly suggestive of Minnekahta limestone lying 

 on Opechee red shale. The latter limestone occiars on the east side of the 

 Laramie Mountains and in the Black Hills, and contains ' Permian ' fossils in 

 the sense in which the Permian is used in the Mississippi Valley. The Forelle 

 limestone may possibly represent the Embar formation." 



A little farther west and south on the west side of the Bighorn Mountains 

 the Embar limestone occurs in the Owl Creek and Wind River Mountains 

 and eastward. 



From the walls of the Bighorn Canyon Girty determined Spiriferina 

 pulchra, which "is believed to characterize a horizon just below the so-called 

 Permo-Carboniferous of the Wasatch Mountains region," and, as Dr. Girty 

 correlates the latter with Permian of the Grand Canyon section, the occur- 

 rence of these fossils in the Embar limestone suggests that this formation is 

 equivalent to the upper Aubrey limestone of northern Arizona. According 

 to Girty: 



"The Embar limestone has a very different fauna from the Kansas Permian, 

 but it may be equivalent to it or even later. The fauna is not related to the Guada- 

 lupian. It occurs in Utah just below the Permo-Carboniferous and is known also 

 in Idaho and Nevada." 



West and north of the Permian deposits in Rio Arriba County, New 

 Mexico, is a large series of red beds which undoubtedly contain Permian or 

 Permo-Carboniferous series deposited in the Basin Province. Cross and Howe" 

 have described the formations around Ouray, Colorado, separating the 

 Cutler formation as Permian from the Dolores (Triassic) above and the 

 Rico and Hermosa (Pennsylvanian) below. An unconformity separates the 

 Dolores from the Cutler, but there is no stratigraphic break between the 

 Permian and Pennsylvanian. The description given by Cross and Howe"^ 



" Girty, in Darton, Bull. Geol. Soc. Amcr., vol. 19, p. 429. 



^ Darton, Bull. Geol. Soc. Amcr., vol. 19, p. 431; Knight, Jour. Geol., vol. x, p. 419. 

 ° Cross and Howe, Bull. Geol. Soc. Amer., vol. 16, p. 461, 1905. 



<• Cross and Howe, Bull. Geol. Soc. Amer., vol. 16, p. 461, 1905; see also U. S. Geological Survey, 

 Professional Paper No. 71, p. 480. 



