656 REPORT OF NATIONAL MUSEU.M, 1904. 



Upper Cretaceous, these Laramie rocks which, if Cretaceous at all, 

 were certainly at the very top of the Upper Cretaceous, must repre- 

 sent a great and important period wholly unrepresented in any other 

 part of the world. 



Further, the finding- of evidence of an abundant mammalian life 

 (Tertiary) immediately following- the Laramie period, which in itself 

 contained only Cretaceous vertebrate remains (dinosaurs), suggested 

 to him a sudden ushering in of the Tertiary types which could be 

 accounted for only on the supposition that such originated elsewhere, 

 and were contemporaneously in existence with the Cretaceous forms, 

 i. e., prior to the close of the Laramie period. Their apparent sudden 

 appearance could then be accounted for on the supposition that the 

 physical barrier was removed by somet>f the various earth movements 

 connected with the evolution of the continent. 



To these same opinions he held in his report for 1878, adding that, 

 if the conclusions of all the leading paleontologists regarding the 

 Eocene-Tertiary age of the Wasatch, Green River, and Bridger groups 

 be accepted, "then is there additional evidence of the correctness of 

 the view that the Laramie is a transitional group between the Creta- 

 ceous and Tertiary, partaking of the faunal characteristics of both 

 periods." 



Hayden, in his report for this year (1878), argued that the Fort 

 Union beds of the upper Missouri River are the equivalent of the 

 Lignitic formation, as it exists along the base of the Rocky Mountains 

 in Colorado, and of the Bitter Creek series west of the mountains; 

 also that it was probable that the brackish-water beds on the Upper 

 Missouri must be correlated with the Laramie, and that the Wasatch 

 group, as now defined, and the Fort Union group are identical as a 

 whole, or in part, at least. 



In his report on the systematic geology of the Fortieth Parallel 

 Survey (1878), King again attacked the advocates of the Eocene age of 

 these beds. He reviewed the evidence and announced his convictions, 

 as before, in favor of their being Cretaceous. 



He agreed with Hayden in regarding the Laramie and underlying 

 Fox Hill as strictly conformable, but found a very decided unconforma- 

 bility between the uppermost Laramie containing the dinosaur remains 

 and the immediately overlying rocks of the Vermilion Creek group, 

 which carried mammalian remains. The unconformity here mentioned 

 for the first time is, with the exception of the suggestion made by Peale, 

 perhaps the most important feature yet introduced into the discussion, 

 and it is probable, as elsewhere suggested 1>} T King, that had Hayden 

 seen this locality earlier, the question as to the exact position of the 

 Laramie beds might never have arisen. 



