42 CARBONTFKROUS FORMATIONS AND FAUNAS OF COLORADO. 



tlic C'urlionitVi'ous. 'I'lic lautial list mi pao-o l-tC of King's report comprises Myalina 

 (rcscmliliiii;' xiihiiiiKdnild). Mij((liii(f \\. sp., BdkewelUa parva, Pleurojihornx sp., and 

 Macrodoii sp. King rcinarlcs: "These are the only fossils obtained in Uinta Range 

 from the easily eroded beds that separate the lower sandstones of the Trias from the 

 Belleroplion cherts which mark the uppermost horizon of the Coal Measures, and are 

 interesting, since the forms as well as the physical condition of the beds ai'e closely 

 allied to the rermo-Carboniferous of Weber Canyon.'' The fauna docs, indeed, tend 

 to confirm King's correlation with the Wasatch section, but, as previouslj' remarked, 

 some doubt exists as to whether it belongs in the Permian or Mesozoic. Another 

 less important instance seems to be the fact that Khig ascribes to the Upper Coal 

 Measure limestone a thickness of but from 2,000 to 2,500 feet, while this is stated \>y 

 Powell as 5,305 feet, if I am justified in combining the measurements of the upper 

 Aubrey, lower Aubrej% Ked Wall, and Lodore groups given by him on page 57. 

 Furthermore, Powell describes a great unconformity as occurring at the top of the 

 Uinta sandstone which he believes to be pre-Carboniferous in age. The geologists 

 of the Fortieth Parallel Survey did not ascertain the unconformity noted by Powell. 

 The}' refer this important formation to the Carboniferous, correlating it with the 

 Weber quartzite of the AVasatch section. From the Weber quartzite a fairly satis- 

 factory fauna is known, which proves the age of the formation to be beyond doubt 

 Upper Carboniferous. As to the age of the Uinta sandstone, but little paleontologic 

 evidence exists. Powell found it to be completely unfossilif erous, and the only fossils 

 obtained b}' the Fortieth Parallel Survej^ were not found in place. They consist of 

 a crinoid column, half of a ribbed brachiopod, somewhat doubtf ulh' referred by Hall 

 and Whitfield to Spirifer imhrex, and a well-preserved specimen of Splrifer camer- 

 attm. The Spirifer iinbrex was found upon the slopes of Mount Agassiz, and the 

 horizon is believed to be about TOO feet below the summit, and certainlj' as much 

 or more beneath the top of the Uinta sandstone. Spirlferii of the tinh'ex type are 

 unknown in the Devonian, and are especially characteristic of the Lower Carbonifer- 

 ous. It would hardly be safe to infer from this specimen more, however, than that 

 the age of this horizon is probabh' Carboniferous, without reference to any division 

 of the Carboniferous series. The crinoid column could not be taken to indicate much 

 more than an age probably subsequent to the Cambrian, but in view of local facts of 

 lithologic and stratigraphic occurrence, it may well belong to Carboniferous time. 

 The Spirifer cameratus was found in a pebble of red jaspery quartzite near Geode 

 Canyon, and its origin was evidently the Weber quartzite beds of the interior of the 

 range, while the character of the matrix would indicate that the stratum in which it 

 was deposited belonged to the middle of the series." Spirifer cameratus is a distinctly 

 Pennsylvanian species, and forms even resembling it are very rare in the Mississip- 



aV. S. Geol. Expl. 40th Par., Kept., vol. 2, 1877, p. 290. 



