94 C. A. White — On the Bear Hiver Formation, etc. 



Upon the sheet of the general atlas of the U. S. Geological 

 Survey of the 40th parallel which shows the district traversed 

 by Bear River, the Bear River formation is indicated as be- 

 longing to the Laramie, and the areas which it was then known 

 to occupy are colored in the same manner as are the true 

 Laramie areas. This atlas was published in 1876, and the 

 geology of the Bear River district is understood to be the 

 joint work of Messrs. Clarence King and S. F. Emmons. 



In his final report also Mr. King assigned the Bear River 

 strata in question to the Laramie ;* and he correlated those of 

 the originally discovered locality near the mouth of Sulphur 

 Creek with the uppermost beds of the true Laramie at Black 

 Buttes. Mr. Emmons also, in his final reportf assigned the 

 same strata to the Laramie. 



At this time the belief had become general that the Bear 

 River formation, notwithstanding the material difference of 

 its fossil fauna from that of the great formation which then 

 began to be known by the name of Laramie, was contempo- 

 raneous with the latter, and that both hold the same relation to 

 overlying and underlying formations. For these and other 

 reasons the Bear River formation began, as already mentioned, 

 to be known as the Bear River Laramie ; that special designa- 

 tion indicating a recognition of the faunal difference between 

 it and the Great Laramie formation. 



The final report of Mr. Engelmann was not published until 

 187.64 sixteen years after the publication of his original report, 

 when discussion as to the true geological age of the Laramie 

 formation, including the Bear River strata, had become some- 

 what prevalent.. Apparently influenced by these discussions 

 Mr. Engelmann in this report expressed the belief that the 

 Bear River strata are of Cretaceous age, although in his origi- 

 nal report (loc. cit. ) the opinion that they are of Tertiary age 

 is plainly stated. 



Mr. Meek's final report to Captain Simpson on the fossils of 

 the Bear River formations is contained in the same -volume 

 with that of Mr. Engelmann (op. cit.) ; and in his discussion 

 of them he too was disposed to assign them to the Cretaceous, 

 but he nowhere indicates a doubt that the taxonomic position 

 of the Bear River formation is the same as that of the true 

 Laramie. He also expressed this opinion in his last published 

 writing,§ where also he described and figured several of the 

 characteristic Bear River species. 



*U. S. Geol. Surv. 40th Parallel, vol. i, p. 373 and map III. 

 f U. S. Geol. Surv. 4oth Parallel, vol. ii, p. 327. 

 % See Simpson's Report Great BasiD of Utah, pp. 247-33G. 

 § U. S. Geol. Surv. 40th Parallel, vol. iv, p. 1 63. 



