240 STANTON 



dinosaurs and small primitive mammals has been found. This forma- 

 tion has been called by various names, such as " Ceratops beds of 

 Converse County," "Lance Creek beds," and "Hell Creek beds," 

 and it has furnished almost all of the "Laramie" vertebrates that 

 have been described except those from the Judith River formation 

 vi^hich was once considered part of the Laramie but is now known to 

 be older. It has also yielded a considerable invertebrate fauna and 

 a flora of more than loo species. 



The "Ceratops beds" have always been referred to the Cretaceous 

 by those who have studied their faunas, while the paleobotanists 

 have often contended for the Tertiary age of floras from beds con- 

 siderably older than these. Recent papers by Whitman Cross' and 

 F. H. Knowlton^ have again raised the question concerning the bound- 

 ary between Cretaceous and Tertiary by arguing that these " Ceratops 

 beds" and other formations grouped together by Doctor Cross under 

 the term Shoshone are Eocene. Doctor Knowlton goes farther and 

 places the "Ceratops beds" in a lower member of the Fort Union 

 formation, entirely above the Shoshone group. His argument for the 

 Eocene age of these beds is based chiefly on (i) unconformable rela- 

 tions with the underlying marine Cretaceous and an inferred long period 

 of erosion before they were deposited; (2) stratigraphic continuity and 

 close floral connection with the overlying Fort Union which is generally 

 admitted to be Eocene. He also holds that the invertebrate fauna 

 has Tertiary rather than Cretaceous affinities and that the vertebrates 

 afford no positive evidence of Cretaceous age. 



The purpose of the present paper is to show that some of the data 

 already used in the discussion are capable of a different interpretation 

 and to call attention to some additional facts which ought to be fully 

 considered before a final verdict is reached. All are agreed that the 

 strata in question are near the boundary between Cretaceous and 

 Tertiary. My opinion is that the greater weight of evidence places 

 them on the Cretaceous side. The general question is still under 



• Cross, Whitman: The Laramie formation and the Shoshone group. Proc. 

 Wash. Acad. Sci., Vol. XI, No. i, 1909, pp. 27-45. 



* Knowlton, F. H.: The stratigraphic relations and paleontology of the 

 "Hell Creek beds," "Ceratops beds," and equivalents, and their reference 

 to the Fort Union formation. Proc. Wash. Acad. Sci., Vol. XI, No. 3, 1909, 

 pp. 179-238. 



