cretaceous age of the coal of Brush Creek, a locality from 150 to 200 miles 

 distant. So with the determination from "Weber River (Coalville) 200 miles, 

 and Evanston and Sulphur Creek 150 miles distant, on the opposite side 

 of the Bridger Basin. He did not regard these as determinations affect- 

 ing the age of the Bitter Creek Beds any more than they did of the Eoeene 

 coal of Osino, 200 miles west of them. 



The only approximations to the point were made by Mr. Meek. In 

 King's Survey of the 40th Parallel ( 1. c. 462), Mr. Meek's nearest points 

 of investigation were the shell beds of Sulphur Creek (Bear River) ; of 

 these he says, ' ' While I am, therefore, willing to admit that facts may 

 yet be discovered that will warrant the conclusion that some of these 

 estuary beds should be included rather in the Cretaceous than in the Ter- 

 tiary, it seems to me that such evidence must either come from included 

 vertebrate remains, etc." This is not vei*y conclusive, and acknowledges 

 in advance the importance of the determination of vertebrates from the 

 same neighborhood ( Evanston), and from Bitter Creek, above described. 

 Secondly, in Hayden's Survey, 1870, p. 298, the only determination of the 

 age of coal of the Bitter Creek area is tertiary (Hallville). Thirdly, in 

 Hayden's Survey Montana, etc. (1871, p. 375), Mr. Meek enumerates 

 three species from this region (Point of Rocks) as cretaceous, every one 

 with question as to determination, which, therefore, decides little as to 

 the age of the beds. In the same way all his Coalville species are marked 

 with question. In his earliest investigation in connection with Mr. Engle- 

 man, in Capt. Simpson's Report (1860), he expressly states that the age 

 of the Bitter Creek coal series is unknown. 



Thus it seems that a knowledge of the literature of the geology of the 

 Bitter Creek coal, shows : I. The Messrs. King and Emmons on strati- 

 graphic evidence referred the lower part to the cretaceous and the upper 

 to the tertiary. That on Palseontological grounds, II. Mr. Lesquereaux 

 regards them as tertiary; III. Mr. Meek's evidence is doubtful; * and, IV. 

 Dr. Hayden has believed in a transition series. 



Hence it appeared to the speaker, that the explorations directed by Dr. 

 Hayden during the past season had contributed largely to our knowledge, 

 proving the existence of an interruption between the cretaceous and ter- 

 tiary formations ; less it is true than that which exists elsewhere, and 

 similar to that insisted on by Clarence King's survey in the region of 

 Bear River and the Wahsatch country. 



* This gentleman has stated in a letter to the writer that Bitter Creek Beds constitute a "new 

 zone." 



