JURASSIC. 571 



L 11. EASTERN OREGON. 



In the Blue Mountains of eastern Oregon occurs a red sandstone from which 

 Jurassic fossUs were obtained on Beaver Creek, a tributary of Crooked River. The 

 fauna is that of the Hardgrave sandstone of the Taylorsville district, Cahfornia, 

 and is assigned by Hyatt ^®* to the Lias (Lower Jurassic) . Hyatt mentions other 

 locaUties at which there are characteristic occurrences of the same fauna and infers 

 a connection between them extending from Inyo County, Cal., to the Blue Mountains. 



L 12. MONTANA AND WYOMING. 



The Jurassic of the Philipsburg quadrangle, Montana, is thus described by 

 Calkins:'' 



The beds immediately overlying the Quadrant formation in the Philipsburg quadrangle ia 

 southwestern Montana are correlated with the Ellis formation on lithologic and paleontologic 

 grounds. 



The Elhs in this area consists mainly of calcareous shales and sandstones and impure 

 ferruginous limestone; locally it contains, near the middle, some conglomerate whose pebbles 

 are mainly of chert like that in the Madison limestone. These rocks all weather in ocher- 

 yellow colors which are characteristic of the formation as here developed. 



The thickness of the formation on Gird Creek about 5 miles southeast of Stone, Mont., is 

 about 400 feet. It is thinner in places and seems locally to be absent in a small area southeast 

 of Twin Peaks. It appears to be structm-ally conformable with the Quadrant, but the absence 

 of any deposits belonging between the Carboniferous and Jurassic marks a distinct hiatus. 



T. W. Stanton has collected characteristic Ellis fossils from the formation on Gird Creek 

 and on the Ovardo road about 6 miles east of Drummond. Those collected on Gird Creek lie 

 from 50 to 100 feet above the Quadrant formation. They comprise the following forms: 



Ostrea strigilecula White. 

 Camptonectes pertenuistriatus H. and W. 

 Eumicrotis curta Hall. 

 • Trigonia sp. 



Pleuromya subcompressa Meek. 



In this section east of Drummond calcareous beds from 200 to 250 feet above the Quadrant 

 have yielded: 



Rhynchonella gnathophora Meek. 



Ostrea sp. 



Camptonectes bellistriatus Meek. 



Lima? sp. 



Cucullea haguei Meek. 



Tancredia? sp. 



Pleuromya subcompressa. 



A conglomerate near the top of the Ellis formation here contains Rhynchonella gnathofhora 

 Meek, Ostrea sp., and Gervilia sp. 



For an account of the Ellis formation as developed in Yellowstone Park, the 

 Yellowstone folio ^^^ may be consulted. In that region the formation consists of a 

 lower limestone division and an upper one chiefly of sandstone. The limestones 

 are impure, argillaceous and gray, and associated with shales, and they carry marine 

 fossils at several horizons. The upper sandstone member varies from a coarsely 

 crystaUine, fairly pure limestone carrying an abundance of fragmentary fossils to a 

 true sandstone with conglomerate layers. 



a Unpublished manuscript. 



