STRATIGRAPHIC SUMMARY. 635 



below it, represent what there is of the Mississippic. The Wood- 

 ford is often in part referred to the Devonic, but the fossil evidence 

 is not conclusive. The basal part of the Caney is regarded by 

 Girty as late Mississippic (possibly equivalent to the Moorefield, 

 Batesville and Fayetteville beds of northern Arkansas) and con- 

 tinuing into the lower Carbonic (Pottsville). At the base of the 

 Caney there is sometimes the Sycamore limestone.^^ 



In the Ouachita mountain area, the Caney shale rests upon the 

 Jackfork sandstone, and this in turn rests upon the Standley shale, 

 below which, after a disconformity, occur Ordovicic cherts (Tali- 

 hina chert). The fossil plants of the Standley shale suggest late 

 Mississippic, or early Carbonic age. 



In the Sierra Ladron of New Mexico, the Lake Valley limestones 

 represent part of the Mississippic. 



In the Front Range region of Colorado, the Millsap limestone 

 represents what there is of the Mississippic. In the Black Hills, 

 two limestones, the Englezvood, resting disconformably on the 

 Ordovicic, and the Pahasapa, next above, represent the Mississip- 

 pic. In west central Colorado, the Leadville limestone bounded 

 above and below by disconformities represents a part of this hori- 

 zon, while in southwestern Colorado, the Ouray limestone in part 

 Devonic, represents lower Mississippic and is disconformably over- 

 lain by Carbonic beds. In the Grand Canyon, the Red Wall lime- 

 stone is referred to the Mississippic, resting disconformably on 

 Devonic beds, while th^ Escabrosa limestone of the Bisbee Arizona 

 regions holds a similar position. In the Wasatch Mountains, the 

 lower part of the Wasatch limestone is referred to the Mississippic 

 and in the Uintah Mountains, the same series is slightly represented, 

 the Lodore shale of the eastern Uintahs, probably belonging here. 



In central Montana, the Madison limestone, 1,000 ft., with a 

 Choteau fauna, rests upon Devonic (?) beds and is succeeded by 

 1,400 feet of Quadrant shales and limestones above which lies the 

 Jurassic. In central Nevada (Eureka district) the White Pine 

 shale, with a fauna similar to that of the Caney shale of Okla- 

 boma^^ succeeds the Devono-Mississippic Nevada limestone, and is 

 succeeded by the Diamond Peak Quartzite, and this by coal-mea- 

 sure beds. 



^* Tishomingo Folio. 



^ Girty, Bull. Z77, U. S. G. S., p. lo, footnote. 



