38 CAKBUNIFEKOUS FuKMATIOHS AND KAUNAS OK OOLOKAUO. 



as it is hiolily proliiililr. froiu its lithologic composition, that tlio LodoriMlocs not 

 belong to tilt" Mississippian limestone series of the West, it must lie of Upper 

 Carboniferous ag-e. King cites a few species of unniistukable Pcmisylvanian age 

 from 60 feet above the Wcbei- tpiartzite, a horizon which must be in the Lodore 

 group and below the Red Wall limestone of the Uinta section. 



I siiall latei' offer some evidence tending to show that tlie lower portion of the 

 Uinta sandstone is Cambrian and the upper portion Upper Carboniferous (Weber 

 quartzite). If this is so, the Grand Canyon series of the Grand Canyon section would 

 probably be equivalent to the Red Creek qiiartzite of the Uinta section, and the Tonto 

 sandstone to the lower part of the Uinta sandstone, while the Devonian and the true 

 Red Wall limestone would probably be wanting. It remains to find the equivalent in 

 the Grand Canyon section of the Pennsy^lvanian portion of the Uinta sandstone and 

 of the beds which Powell called the Lodore group, the Red Wall limestone, and the 

 upper and lower Aubreys groups. On the whole it seems to me most probable that 

 the four formations last mentioned represent the Aubrey group of Gilbert. The 

 lithologic character of the series is not unlike, and in a general way Powell traced 

 their equivalence in the Held. The paleontologie evidence is partly^ favorable and 

 partly^ adverse to this correlation. From the Aubrej' group Gilbert cites Productus 

 ivesii, Productus sejnireticulatus, Spirifir lineatus, Seminula suitilita, MeekeUa sp. , 

 Derbya sp., Avioulqpecten cf. ocoidentalis (p. 177). Most of these are well-known 

 Pennsylvanian species of the Mississippi Valley section; but I am inclined to 

 question the exact identity iu some cases. Newberrv, however, had previously 

 described a number, of species from this horizon, namely, Archseoddarls longis- 

 innis, Archseocida/ris ornaims, Archmocidaris gracilis^ MeekeUa occidentalism Meek- 

 eUa j^y'd-^nidaUs, Chonetes ti&rneuilanus, Proditctus costatoides, Productus ivesii, 

 Productus occidentalism Productus costatus, Productus semireticulatus, Spirifer 

 lineatus, Seminula suhtilita, Avicidopecten coloradoensis, Allerisma capax, etc." 

 Many of these species are new and are not known to occur iu the Mississippi 

 Valley. To this list may be added Productus suihorridus Meek, which is 

 found at this horizon. From the lower Aubreys group, at the junction of the 

 Grand and Green rivers, White cites some of the same forms, among them Pro- 

 ductus ivesii, which appears to be especially characteristic of the Aubrey formation. 

 As associated with it is mentioned also Productus multistriatus, a species whose 

 horizon in the Wasatch Mountains is in the Upper Coal Measure limestone, a series 

 which 1 provisionally^ regard as correlated with the Aubrey group of the Grand Can- 

 yon country^, and with the four formations of the Uinta sandstone now under consid- 

 eration. This evidence is of course very slender, and must be reenforced by a full 

 consideration of all these faunas, a task to which I shall address myself at some future 



.a Ives's Report Colorado River of West, Senate Ex. Doc. No. — , Thirty-sixth Congress, first session, 1861, pp. 116-129, 



