LARAMIE AND FORT UNION BEDS 293 



Phyllites cupanioides is noted in Newberry's^ list as occurring only in 

 the Fort Union. 



As a result of two summers of field work in North Dakota, the 

 very definite impression remains that, at least in that state, there is 

 great difficulty in retaining the term "Fort Union beds," since they 

 never have been, and apparently cannot be, set off from the Laramie 

 either in vertical or horizontal extent. The conclusion of White^ 

 seems to be wholly justified: 



In eastern Montana and western North Dakota the Laramie strata are 

 similarly connected, by specific identity of molluscan remains and by apparent 

 continuity of sedimentation, with those which there are reported to bear a purely 

 Tertiary flora, and which have generally been designated the Fort Union group. 



From the standpoint of paleobotany, Clark^ indicates that the 

 same conclusion may be reached. He quotes Professor Newberry,^ 

 who held that the two formations should be referred to different 

 horizons, the Laramie to the Cretaceous, and the Fort Union to the 

 Tertiary. These quotations he follows immediately with others from 

 Professor Ward, who, discussing the statements of Dr. Newberry, 

 says: 



that, although the difference in flora exists, "yet the Laramie and Fort Union 

 must go together," and offers in explanation "that possibly the latitude, taken in 

 connection with a different topography, such as may have existed in the two 

 regions, might account for the great difference in the floras." Professor Ward 

 further gives a list of eight identical species from the Laramie and Fort Union 

 groups. 



Knowlton^ also holds that there can be scarcely any doubt that 

 the flora of the Upper Laramie, of the Atanekerdluk series in Green- 

 land, and of the Spitzbergen and Alaskan territories is identical with 

 the Fort Union flora of the Missouri region. 



In mapping North Dakota, therefore, there seems to be no satis- 

 factory reason for noting Fort Union beds as distinguished from the 

 Laramie. Indeed, to make such a distinction seems practically 



impossible. 



Frank A. Wilder. 



University of Iowa, Iowa City, 

 April 30. 1904. 



1 Monograph XXXV, The Later Extinct Floras of North America, p. 150. 



2 Bulletin No. 82, U. S. Geological Survey, p. 149. 



3 Ibid., Bulletin No. 8j, p. 135. 



4 Geological Society of America, Bulletin, Vol. I (1890), pp. 524-27. 



5 Proceedings of the National Museum, Vol. XXVII (1894), p. 240. 



