CHAPTER III. 



DESCRIPTION OF THE BASIN PROVINCE. 



The region yielding Permo-Carboniferous fossils, in Rio Arriba County, 

 New Mexico, has already been twice described by the author and Dr. Willis- 

 ton." As shown by the faunal lists (p. 96), the animals of the Plains and 

 Basin Provinces were quite distinct, not a single species and but a few doubt- 

 ful genera being common to the two. Whether the deposits in the two prov- 

 inces are of the same age or the western younger than the eastern is as yet 

 undecided. Dr. Williston believes that the fauna from the New Mexican 

 beds is more primitive, and so younger than that from Texas and Oklahoma. 

 Dr. Schuchert is inclined to believe the New Mexican deposits younger from 

 the evidence of the invertebrates. The Hueconian fauna of Girty ^ is "quite 

 different from those of the Pennsylvanian of the Mississippi Valley and are 

 mostly undescribed." The Guadalupian life "is quite unlike the faunas of 

 eastern North America, and almost equally unlike those of the West." Girty 

 also remarks that the Hueconian fauna is likely to be found widely extended 

 in the West. 



In Wyoming there are two distinct faunas which are closely approxi- 

 mated, geographically. Knight found invertebrate fossils near Red Moun- 

 tain, Wyoming (plate 16, fig. i), distinctly similar to those of the Kansas 

 Permian (?) limestones, but farther west a different fauna occurs. In 

 detail : 



Near Red Mountain Knight'' found, 728 feet above the base of his section, 

 a fossiliferous layer of "grayish to reddish sandstone containing the following 

 genera of fossils: AUorisina, Pleurophorus, Bellerophon, Myalina, Aviculo- 

 pecten, Dentalliiim (?), Pleurotomaria (?), several small gastropods, and some 

 remains of vertebrates. * * * The genera (in the fossiliferous layer in this 

 section) are so characteristic that it is unnecessary to discuss their geological 

 position ; they belong to the Paleozoic and resemble to a marked degree the 

 fossils of the Kansas and Nebraska Permian." (Plate 16, figs, i and 2, and 

 plate 17, fig. 2.) 



In the Park City mining district Bartwell^ distinguished three forma- 

 tions, the Woodside, Thaynes, and Ankareh:' 



"The Woodside is a fine-grained unfossiliferous red shale 700 to 1,180 feet 

 thick, which overlies unconf ormably the Park City formation (Pennsylvania) . The 

 Thaynes is characteristically calcareous and rich in fossils. It is 1,190 feet thick. In 



"Williston and Case, Jour. Geol., vol. xx, p. i, 1912; Carnegie Inst. Wash. Pub. 181, p. i, 1913. 



'' Girty, U. S. Geological Survey, Professional Paper No. 58. 



" Knight, Jour. Geol., vol. 10, p. 419. 



'' Bartwell, Jour. Geol., vol. 15, 1907, p. 439. 



» Qufjtcd from U. S. Geological Survey, Professional Paper No. 71, p. 494. 



72 



