UPPEE CRETACEOUS. 685 



lithologic and paleontologic evidence. * * * At the beginning of the field season, in the 

 absence of definite fossil evidence, differences in lithology alone were accepted as a basis for the 

 subdivision into formations. A subsequent study of the fossils, both in the field and in the 

 laboratory, by T. W. Stanton and F. H. Knowlton, has shown that the lithologic units do not 

 coincide in all particulars with the formations as they are recognized -farther north and else- 

 where. Fossils collected at various localities in the fields point to the presence of the Eagle 

 and Laramie formations, though the evidence is not conclusive, as many of the species are either 

 new or heretofore unknown to the formations, and strictly characteristic specimens are lacking. 

 A fresh-water fauna which contains forms suggestive of upper Montana occui's in beds between 

 the Eagle and Laramie (?). There is abundant fossil evidence to prove the presence of the 

 Fort Union formation. A suggestive break occurs at the base of the conglomerate beds noted 

 in the table, which was thought in the field to be an unconformity at the base of the Fort Union, 

 but later study of the plant collections shows that Fort Union forms occur a few feet below this 

 horizon. As the final determinative' evidence has not been obtained, the divisions shown in 

 the table are only provisionally introduced. 



For notes on the northeast side of the Bighorn Basin, see L 12-13 (p. 690). 



K-L 13. SOUTH DAKOTA AND NOBTHWESTEBN NEBBASKA. 



Darton ^^^' ^^^' ^^' ^^^ has described the strata of South Dakota and northwestern 

 Nebraska in several pubUcations. In the Newcastle folio ^^° he gives the local 

 development of the Cretaceous as follows : 



Upper Cretaceous: Feet. 



« Laramie f ormation^ — massive soft buff sandstone with concretions and carbonaceous shajea. 800 



Fox Hills formation — thin hard sandstone in sandy shale, and soft clayey sandstone below. 75-150 



Pierre shale — dark gray shale or clay with concretions containing many fossils 1,250 



Niobrara formation — gray calcareous shale, and impure chalk 200 



Carhle formation — variable gray shale 700 



Greenhorn limestone — thin bedded, hard gray limestone, with Inoceramus labiatus 50 



Graneros formation — dark shale 1,000 



Dakota sandstone — gray to buff sandstone mostly very massive 50-100 



Lower Cretaceous: 



Fuson formation — gray to red shales with thin sandstones 15-30 



Lakota sandstone — massive cross-bedded gray to buff sandstone, with local coal beds and 



conglomerate 150-200 



Morrison shale — massive sandy shale and fine sandstone 150 



Unconformity. 



L 10. WESTEBN WASHINGTON. 



Cretaceous sandstones are supposed to form a large part of the Olympic Penin- 

 sula, in Washington. Arnold ^'^ examined them on the western coast and states : 



The rocks supposed to be Cretaceous in age, the correlation being based on their strati- 

 graphic position and lithologic character, are confined to the western coast of the peninsula. 

 They extend over most of the territory from 1 i miles south of Point of the Arches to 1 mile north 

 of Cape Elizabeth and consist almost entirely of a coarse gray sandstone, with occasional zones 

 of black shale and rarely a little conglomerate. The thickness of the formation is probably 

 over 5,000 feet, although, owing to its complex structure, this is only a very rough approximation. 



L, 10-11. JOHN DAY BASIN, OBEGON. 



(See Chapter XIV, p. 621.) 



X, 12-13. EASTEBN IDAHO, NOBTHWESTEBN WYOMING, AND MONTANA. 



Cretaceous strata occur here and there in the Yellowstone Park and vicinity. 

 Stanton "^ reported on the strata and their correlation and showed that repre- 

 sentatives of the Colorado and Montana are present. Certain strata which were 



