436 GEOLOGICAL SURVEY OF THE TEEEITORIES. 



fornia, referred to tlie Cretaceous. A Modiola from the same horizon, a,lso, appears to 

 he specifically identical with M. Pedernalis, of Roemer, from the Cretaceous of Texas. 

 Dr. Haydeu also has, from a little above the coal-beds at Coalville, specimens of Osirea, 

 that seem much like 0. Idriaensls and 0. Breiveri, of Gabb, from the upper ijeds of the 

 California Cretaceous. As no other fossils were found directly associated with these 

 oysters, however, nor any marine forms above them, it is possible that they may be- 

 long to the Lower Tertiary. 



From the affinities of some of these fossils to forms found in the latest of the beds 

 referred in California to the Cretaceous, and the intimate relations of these marine 

 coal-bearing strata of Utah to the oldest Tertiary of the same region, and the apparent 

 occurrence of equivalent beds bearing the srme relations to the oldest brackish- water 

 Tertiary beds at the mouth of Judith River on the Upper Missouri, I am inclined to 

 believe that these Coalville beds occupy a higher horizon in the Cretaceous than even 

 the Fox Hills beds of the Upper Missouri Cretaceous series ; or, in other words, that 

 they helong to the closing or latest memher of the Cretaceous. 



These remarks certainly oitgJit to Diake it clear enough, one would 

 think, that I regarded the coal-bearing strata at Coalville, Utah, and 

 near the mouth of Sulphur Creek, on Bear River, Wyoming, as being 

 of Cretaceous age.* A few pages further on in the same report, I gave 

 a list of all the fossils collected during the preceding summer by Dr. 

 Hayden's party, that I referred to the Cretaceous epoch. In this list, it 

 will be seen, I placed all of the few. fossils in the collections then under 

 consideration, from the coal series at Coalville, Utah, and Bear Eiver. 



In making out the Cretaceous list mentioned above, I endeavored to 

 express, by a number opposite the name of each species, the particular 

 horizon in the Cretaceous series of the Upper Missouri, to which the 

 bed that contained it belongs. This I fully explained on page 289 of 

 the same report cited, as follows : " The numbers 1, 2, 3, 4, and 5, along 

 the right-hand margin of the list,t opposite the localities, show to which 

 member of the Upper Missouri Cretaceous each species belongs, the 

 subdivisions of the Upper Missouri Cretaceous having been severally 

 named and numbered from below upward, as follows : No. 1, Dakota 

 group ; No. 2, Fort Bentoji group ; No. 3, Niobrara division ; No^ 4, 

 Fort Pierre group ; and No. 5, Fox Hills beds ; the names being derived 

 from localities where the several formations are well developed." 



In accordance with this plan, I assigned each species in the list to its 

 proper horizon in the Cretaceous series, by adding after the locality, 

 " Cret. No. 1," " Cret. No. 2," &c,, according to .its position, except- 

 ing those from Coalville. These I could not refer to their precise 

 horizon in the Cretaceous, because, although not doubting that they 

 belong to the Cretaceous system, I was, as already explained, in doubt 

 whether the beds in which they were found correspond exactly to any 

 of the recognized subdivisions of the Upper Missouri series, being, as 

 stated, rather inclined to think they form the closing member or divis- 

 ion ol the Cretaceous, holding a position above the horizon of No. 5 of 

 the Upper Missouri section. Consequently, in order to give expression 

 to this doubt, as well as to follow out the system of notation, I placed 

 opposite each of the species from Coalville, and the coal-bearing sand- 

 stones at Bear Eiver, the words " Cret. No. t " meaning thereby, 

 of course, that I was in doubt whether these beds corresponded exactly 

 with any particular one of the recognized subdivisions of the Upper 

 Missouri series ; which, it should be remembered, only represents a jDart 

 of the whole Cretaceous system. 



* Another quite distinct formation at the Bear River locality, containing a peculiar 

 group of fresh and brackish water types of fossils, all entirely difterent from forms 

 found in the marine beds containing the valuable beds of coal there, was referred by 

 me provisionally to the lower Eocene. 



t These numbers were placed on the right-hand margin of the list in the MS., but 

 are not exactly so in the list as printed. 



