C. A. White — On the Bear River Formation, etc 93 



In his official report for 1870 Dr. Hayden republished the 

 substance of his article in the Proceedings of the American 

 Philosophical Society just referred to, in which he again 

 assigned the Bear River formation to the Tertiary, stating its 

 position to be at the top of the Sulphur Creek section. This 

 volume of reports also contains a chapter by Mr. Meek* con- 

 cerning the fossils which were collected by Dr. Hayden during 

 the previous year, in which he assigned to the Tertiary all those 

 species which were obtained from the Bear River formation. 



In. Dr. Hayden's official report for 1871, Mr. Meek again 

 catalogued the fossils from the Bear River formation under the 

 head of Tertiary ;f and in the same year Mr. T. A. Conrad 

 referred this formation to the Lower Eocene upon paleonto- 

 logical grounds.:}: 



In 1872 Mr. Meek, in company with Dr. H. M. Bannister, 

 visited Bear River valley and specially studied the section 

 which is exposed along Sulphur Creek, near its mouth, and 

 which includes besides a great thickness of marine strata those 

 of non-marine origin which have just been mentioned as 

 having been first discovered by Mi". Engelmann. The results 

 of this study were published by Mr. Meek in 1873, § in con- 

 nection with which publication he gave a figure of the section 

 referred to, accompanied by a detailed description of its mem- 

 bers. In this publication he continued to catalogue the fossils 

 of the Bear River formation under the head of Tertiary, but 

 in his remarks upon these strata he for the first time expressed 

 some doubt upon this point, and suggested that they might 

 " belong to the Upper Cretaceous." It is evident, however, 

 that he was still of the opinion that their position is at the 

 summit of the section, and therefore above all the undisputed 

 Cretaceous strata which constitute its other members. 



The character of his discussions concerning the paleontology 

 of the Bear River formation in this and in previous publica- 

 tions shows that the doubt referred to was not entertained on 

 account of any evidence afforded by the fossils obtained from 

 those strata, all of which he regarded as of Tertiary types, but 

 he seems to have been influenced by the fact that dinosaurian 

 remains had then for the first time been discovered in strata 

 now known to belong to the Laramie which until then had 

 been by all geologists regarded as of Tertiary age, as also had 

 been the Bear River formation. 



* Fourth Ann. Rep U. S. Geol. Surv. Terr., pp. 149-153. 



f Fifth Ann. Rep. U. S. Geol. Surv. Terr., p. 376. 



\ This Journal. Ill, vcl. i, pp. 381-383. 



§ Sixth Ann. Rep. U. S. Geol. Surv. Terr., pp. 451-454. 



