RECAPITULATION OF PALEOZOIC FORMATIONS. 197 



his correlations are with the Grand Canyon section, and his nomenclature in large 

 part that employed by Gilbert for strata in northern Arizona. Similarly, Emmons's 

 survey was westward, along the fortieth parallel, through the Uinta Range and into 

 the Wasatch Range. His comparisons are, therefore, with the Wasatch section, and 

 the same nomenclature is employed. I have elsewhere considered at some length 

 the three sections thus bound together in the literature, and need only repeat the 

 outlines of the previous discussion. 



Powell's section, which was made in the eastern end of the Uinta Range, is more 

 detailed than that of King and Emmons. The basal member of the sedimentary series 

 is the Red Creek quartzite, a formation of very great thickness, which will doubtless 

 prove to be of Algonkian or pre-Cambrian age. 



Above the Red Creek quartzite, and separated from it, according to Powell, by 

 an important unconformity', is another great siliceous formation, the Uinta sandstone, 

 which has a thickness of over 12,000 feet. The Uinta sandstone is followed bj^ the 

 Lodore, Red Wall, lower and upper Aubrey, and Shinarump groups, whose char- 

 acters maj' be summarized somewhat as follows: 



The Uinta group consists of sandstones and sandy shales, and is very ferruginous, 

 throughout, the general color being red and brown. Conglomeratic horizons are 

 occasionally found in the series, and at its junction with the Red Creek quartzite 

 there is a basal conglomerate. The thickness is 12,500 feet. 



The Lodore group is said to rest unconformably upon the Uinta sandstone. It 

 is 460 feet thick, and composed of soft sandstones and shales, with conglomerates at 

 the base. Carboniferous fossils have been found in these beds (Powell). 



The Red ^'^'all group consists of cherty limestone on the north flank of the Uinta 

 Mountains, while on the south flank man}' sandstones are intercalated with the cal- 

 careous beds. A measured section in the Uinta Mountains gives the entire thickness 

 as 2,400 feet, but it is elsewhere stated as 2,000 feet.'' 



The lower Aubrey group consists of soft sandstones and intercalated limestones. 

 The thickness found in a detailed section in the Uinta Mountains is 800 feet. It is 

 elsewhere stated as 1,000 feet. 



The upper Aubrey in the Uinta Mountains is composed of two members, a 

 massive, homogeneous, gray sandstone called the Yampa sandstone, and above it a 

 cherty limestone for which the name Bellerophon limestone is employed. The Yampa 

 sandstone has a thickness of a thousand feet or more. The Bellerophon limestone is 

 150 to 200 feet in thickness. The thickness of the upper Aubrey is also given as 

 1,000 feet, and in a detailed section 1,575 feet was measured. 



The Shinarump group is given a thickness of 1,800 feet in the Plateau province 

 section, and consists in the Uinta Mountains of shales and soft sandstones. In the 



a Powell's Kept. Geol. Qinta Mountains, p. 76. 



