40 



direction of the strike/ we were led to suspect considerable lateral displace- 

 ment with faulting, which might very possibly cause the appearance of the 

 same beds both here and at the coal-mines, although at first sight these would 

 appear much higher in geological position. * * I do not know the 

 grounds of Professor Cope's reference of the coal at this point to the Creta- 

 ceous, while he admits the Tertiary age at least of some of the overlying 

 sandstones ; but, as we found no break nor line of demarkation in the whole 

 2,000 feet or more which we examined, and found our fossils in coal-bearing 

 beds immediately above and conformable to the main coal, the facts, so far as 

 they are known to me, do not seem sufficient for such identification." This 

 point offers, therefore, a more complete continuity in stratification and min- 

 eral character, from the Cretaceous to. Tertiary deposits, than any other which 

 I have had the opportunity of examining. 



CONCLUSION. 



Having traced the transition series of the coal-bearing formations ofgthe 

 Rocky Mountain region from the lowest marine to the highest fresh-water 

 epochs, it remains to indicate conclusions. I have alluded but cursorily to 

 the opinions of Mr. Lesquereux and Dr. Newberry as based upon the study of 

 the extinct flora. The former has, as is well known, pronounced this whole 

 series of formations to be of Tertiary age, and some of the beds as high as 

 Miocene. The material on which this determination is based is abundant, 

 and it must be accepted as demonstrated beyond all doubt. I regard the 

 evidence derived from the mollusks in the lower beds and the vertebrates in 

 the higher as equally conclusive that the beds are of Cretaceous age. There 

 is, then, no alternative but to accept the result that a Tertiary Jlora was 

 contemporaneous with a Cretaceovs fauna^ establishing an uninterrvpted succes- 

 sion of life across what is generally regarded as one of the greatest breaks in 

 geologic time. The appearance of mammalia and sudden disappearance of 

 the large mesozoic types of reptiles may be regarded as evidence of migration 

 and not of creation? It is to be remembered that the smaller types of lizards 

 and tortoises continue, like the crocodiles, from Mesozoic to Tertiary time 



'Hayden's AuDual Report for 1872, p. 541. 



2 The circumstance of the discovery of a Mesozoic Dinosaur, Agatlmumas syh-estris, with the cavities 

 of, and between, his bones stnffed full of leaves of Eocene plants (Lesquereux), would prove tliis proposi- 

 tion to.be true, had no other fossils of either kind ever been discovered elsewhere! 



= Griticism of this conclusion bv Professor Dawsou is noticed in the Report U. S. Geol. Snrv. Terrs. 

 1873 ,p. 1 14. 



