58 A. C. Peale — Application of the Term Laramie. 



Before concluding this paper the following point should 

 first be emphasized, viz., the importance of Mr. Yeatch's dis- 

 covery of the great unconformity lying above the Laramie, a 

 discovery the value of which can hardly be overestimated. 

 As he himself says : "The disco very of this great unconformity 

 at all points that have been critically examined over an area 

 of 1000 miles north and south and 250 miles east and west; 

 the fact that it occurs on both sides of the Front Range of the 

 Rocky Mountains, and its great magnitude, all make it one of 

 the most important mile posts in the geological history of 

 western North America. All these considerations suggest 

 anew the first conclusion of Cross in the Denver Region, that 

 this unconformity marks the dividing line between, the Creta- 

 ceous and Eocene in this region." Equally important with 

 this work of Veatch and of Cross is the identification by 

 Knowlton* of the lower Fort Union — the Dinosaur-bearing 

 beds of the Upper Missouri Yellowstone Region — and their 

 more southern extensions in Wyoming and the Dakotas. The 

 misapplication of the term Laramie to these lower Fort Union 

 beds of Knowlton and to the Shoshone beds of Cross was, as 

 already said, inevitable .so long as we were in ignorance of this 

 great unconformity and the entire series was supposed to be 

 conformable. 



The one conclusion we come to from what has been detailed 

 in this paper is the following, viz., the name Laramie should 

 be used only in accordance with the original definition of King 

 and Hayden and be applied only to the beds resting conform- 

 ably upon the Fox Hills Cretaceous. "Whenever we find beds 

 in this stratigraphic position they should be so referred, 

 especially if they contain a Laramie flora, as noted in the 

 original Laramie beds east of the Front Range in Colorado, 

 where there is also an invertebrate fauna comprising at least 

 twenty-five species of shells. 



* Proc. Washington Acad, of Sciences, vol. xi, p. 179 et seq. 



