of the Bear River Formation. 115 



tween Hilliard and Rear River City should be referred to it 

 and it may occur in the upper portion of Oyster Ridge and 

 west of that ridge near Ham's Fork. 



The true Laramie does not occur in the region under discus- 

 sion, unless the coal-bearing series north of Evanston and its 

 equivalent west of Ham's Fork belong to that formation. It 

 has already been stated that the Evanston coal should probably 

 be referred to the Wasatch. 



Corroborative Facts. — (I) The reports of Dr. A. C. Peale and 

 Prof. O. H. St. John* show that this formation extends north- 

 ward beyond Snake River to latitude 43° 45' and covers con- 

 siderable areas. Both these geologists state in their reports 

 that they did not find Cretaceous fossils beneath the Laramie, 

 that is, the Bear River formation. At the few localities where 

 they found undoubted marine Cretaceous its stratigraphic rela- 

 tion to the " Laramie" was not determined. 



(2) Prof. St. John found it impracticable to separate the 

 post-Jurassic formations of his district, and he frequently 

 speaks of the Laramie, meaning the Bear River strata, as con- 

 formable with the Jurassic. 



(3) In the Smith's Fork region Dr. Peale mapped a narrow 

 band between the Jurassic and the "Laramie" as Cretaceous, 

 but he did this only because there is a considerable thickness 

 of non-fossiliferous beds (the " Jurassic " ? of my sections) over- 

 lying the recognized Jurassic and beneath the Bear River for- 

 mation which was then regarded as Laramie. 



(4) The fauna of the Bear River formation is unique. Of 

 the more than thirty species now known in it not one has been 

 found in the true Laramie nor in any of the other fresh-water 

 formations of the West. 



These facts were all perplexing as long as the Bear River 

 formation was placed at the top of the Cretaceous, or in the 

 Tertiary, but they become significant and are much more easily 

 explained when it is known that its true position is near the 

 base of the upper Cretaceous and separated from the Laramie 

 by several thousand feet of marine strata. 



In conclusion it should be stated that my grateful acknowl- 

 edgments are due to Dr. C. A. White whose previous investi- 

 gations had led him to believe that the Bear River formation 

 is older than the Laramie. He accompanied me to the typical 

 localities and identified for me the various points mentioned in 

 previous reports. His suggestions and advice have also aided 

 me greatly in the preparation of this paper. 



* llth Ann. Rept. II. S. Geol. Sur. Terr., pp. 363, etc. : 12th Ann. Rept. Pt. 1, 

 p. 188, etc. ; see also sections on plates 4, 7 and 9 and the maps accompanying 

 the latter report. 



