LANCE FLORA OF EASTERN WYOMING 85 



adjacent strata. The report on this visit was pubhshed in 1897.^ At tliis time 

 Knowlton regarded the plants as indicative of the "true Laramie" age of the "Cera- 

 tops beds," that is, equivalent to the Upper Cretaceous Laramie formation of the 

 Denver basin, and of the same age as the plant-bearing "Black Buttes beds" of 

 southwestern Wyoming. The fresh-water invertebrates and the dinosaurs corrob- 

 orated this conchision. The stratigraphic section, as observed by Stanton and 

 Knowlton, showed a conformable sequence from the Pierre shales up through the 

 Fox Hills sandstone, the "Ceratops beds," and finally the "Fort Union group." 

 The " Fort Union " age of the beds overlying the " Ceratops beds " was determined on 

 plant evidence and on the absence of dinosaur remains.- 



The complete descriptions and discussions of the ceratopsian dinosaurs, includ- 

 ing those of the Lance Creek area, were pubhshed by Hatcher and Lull a decade 

 later.^ The map (plate 51) accompanying that report showed both the exact locah- 

 ties where the dinosaurs had been coUected and the areal hmits of the beds, which 

 were here called the " Converse County beds" and the " Lance Creek beds." ■* The 

 fauna was regarded as of true Laramie (Cretaceous) age, and at least in part con- 

 temporaneous with the dinosaurs from near Black Buttes, Wyoming and from the 

 "Hell Creek beds" of Montana. 



Up to 1909 there was apparent unanimity of pubhshed opinion for the Creta- 

 ceous age of the "Ceratops beds" of the Lance Creek area. In that year, however, 

 Knowlton changed his opinion concerning both their stratigraphic relations and 

 their age. He concluded: 



"Conformably below the beds by some geologists considered as the true Fort Union occur 

 dark-colored sandstones, claj^s and shales, which have often been incorrectly referred to the 

 Laramie, or its equivalent, but which are stratigraphically and paleontologically distinct from the 

 Laramie, and the contention is liere made that these beds, which include the 'Hell Creek beds' 

 and so-called 'somber beds' of Montana, the 'Ceratops beds' or 'Lance Creek beds' of Wyoming, 

 and their stratigraphic and paleontologic equivalents elsewhere, are to be regarded as constituting 

 the lower member of the Fort Union formation, and are Eocene in age." * 



In this paper Knowlton included a revised hst of the plants coUected from the 

 "Ceratops beds" of the Lance Creek area; this differed considerably from the one 

 previously pubhshed.'^ Of 48 recognized forms, only 16 species were specificaUy 

 identified; of 14 species having an outside distribution, 9 were reported known from 

 the Fort Union. In view of the fact that 6 of these 9 species were not mentioned in 

 Knowlton's previous hsts and have not been seen in any of my own larger collections 

 from the "Ceratops beds," I have been much concerned about their validity. An 

 examination of Knowlton's coUections at the U. S. National Museum has revealed 

 that the specimens representing 4 of the species were actually collected from the 

 acknowledged Fort Union beds above the top of the "Ceratops beds," and those 

 representing 3 species are not to be found. The remaining 2 species, Sequoia norden- 



' Stanton, T. W., and Knowlton, F. H., BuU. Geol. Soc. Amer., vol. 8, 127-156, 1897. 



' Ibid., 134, 135. 



' Hatcher, J. B., and Lull, R. S., U. S. Geol. Surv. Mon. 49, 1907. 



< Ibid., 180, 184. 



' Knowlton, F. H., Proc. Washington Acad. Sci., vol. 11, 180, 1909. 



« Stanton, T. W., and Knowlton, F. H., op. cit., 136, 1897. 



