650 REPORT OF NATIONAL MUSEUM, 1904. 



He summed up his evidence as follows: It thus becomes manifest 

 that the paleontological evidence bearing on the question of the age 

 of this formation, so far as yet known, is of a very conflicting nature; 

 though aside from the Dinosaur bones (found by him at Black Butte 

 in 1*872) the organic remains favor the conclusion that it is Tertiary. 

 The testimony of the plants, however, on this point, although they 

 doubtless represent what would be in Europe considered as clearly a 

 Tertiary flora, is weakened by the fact that we already know that 

 there is in Nebraska, in clearly Cretaceous rocks, a flora that was 

 referred by the highest European authority to the Miocene. 



In the report for 1<S73 (printed in 1874) Lesquereux returned once 

 more to the subject and answered more or less satisfactorily various 

 objections which had been made to his previous conclusions. He 

 referred to the Eocene (Lower American Eocene) all the coal strata 

 of the Raton Mountains; those of the Canyon City coal basin; those of 

 Colorado Springs; those of the whole basin of central and north Col- 

 orado extending from Platte River or from the Pinery divide to south 

 of Che}'enne, including Golden, Marshall, Bowlder Valley, Sand 

 Creek, etc.; and in Wyoming, the Black Butte, Hallville, and Rock 

 Spring coal. He considered as American Upper Eocene or Lower 

 Miocene the coal strata of Evanston, and from identity of the charac- 

 ters of the flora, those 6 miles above Spring Canyon near Fort Ellis, 

 those of the localh^ marked near Yellowstone Lake among basaltic 

 rocks, and those of Troublesome Creek, Mount Brosse, and Elk Creek, 

 Colorado. The coal from Bellingham Bay, in Washington, he would 

 also refer to the same horizon. To the Middle Miocene he would 

 refer the coal basin of Carbon and those of Medicine Bow, Point of 

 Rocks, and Rock Creek; to the Upper Miocene, the coal of Elko 

 Station, Nevada. 



Concerning the evidence of invertebrates regarding the Cretaceous 

 age of these beds, he simply remarks: 



I regarded and still regard the presence of .some scattered fragments of Cretaceous 

 shells as of little moment in comparison with the well-marked characters of the flora, 

 characters which have been wholly established by a large number of specimens 

 obtained from all the localities referred to the Lignitic. 



Cope, in his report for this same year, was inclined to agree with 

 Hayden in thinking that the period of the deposition of the sediments 

 of this Lignite or Fort Union group, as it was also called, was one of 

 transition from marine to lacustrine conditions and added: 



It appears impossible, therefore, to draw the line satisfactorily without the aid of 

 paleontology, but here, while evidence ot interruption is clear from the relations of 

 the plants and vertebrate animals, it is not identical in the two cases, but discrepant. 



He then went on to discuss the evidence as given by the various 

 workers, and referring to Lesquereux and Newberry's opinions, based 



