AMERICAN GEOLOGY THE LARAMIE QUESTION. 655 



so far as it relates to marine formations, but when land formations are 

 considered, the plant remains should be given precedence." 



Meanwhile. Dr. C. A. White, paleontologist, became connected with 

 the Hayden survey, being assigned for his first season's work (1877) 

 to the area of northwestern Colorado. In this connection he came 

 quickly in contact with the problem we have been discussing, and 

 early committed himself in favor of the post-Cretaceous age of the 

 beds in question. 



He argued that it was a well-known fact that the evolutional advance 

 of the vegetable kingdom had been greater on this continent than in 

 Europe. Hence, a student of the flora of the American strata, using 

 a series of European standards, would naturally refer those which he 

 found to contain certain vegetable forms to the Tertiary period, while 

 the associated or superimposed remains of animal life might all show 

 them to be of Cretaceous age. according to the same series of Euro- 

 pean standards. 



Taking into consideration the fact that the physical changes which 

 took place in western North America during the Mesozoic and 

 Cenozoic periods were very gradual and without any important break, 

 he would be led to expect to find those animals, whose existence was 

 not necessarily affected by a change from a saline to a fresh condition 

 of the waters, to have propagated their respective types beyond the 

 period which those types in their culmination distinctly characterized. 

 For this reason he felt that these perpetuated types did not necessarily 

 prove the Cretaceous age of the strata, they being evidently the" last 

 of their kind, and because, moreover, all the other known fossil 

 remains of the group indicated a later period. He would, therefore, 

 refer the beds, which had now, according to an agreement between 

 King and Hayden, become known as the Laramie, to a post-Cretaceous 

 age. 



Referring again to the matter in his report for 1877, White conceded 

 that Cretaceous types (dinosaurs) of vertebrate animals were found in 

 the higher strata of the Laramie group and did not question the cor- 

 rectness of referring the plant remains even of the very lowest beds 

 to the Tertiary; noting also that the invertebrate fossils were indeci- 

 sive, since the species were new to science and could not be safely 

 compared with those found elsewhere. Without committing himself, 

 he then offered a suggestion in effect as follows: Since none of the 

 American Cretaceous could be considered as equivalent to the Lower 

 Cretaceous of other parts of the world, but must be considered as 



a Marsh, it may be noted incidentally, in 1877, in discussing the problem of the 

 boundary between the Cretaceous and Tertiary, announced that in his opinion the 

 evidence of the numerous vertebrate remains was decisive in favor of the Cretaceous 

 view. 



