16 



led to suspect considerable lateral displacement with faulting, which 

 might very possibly cause the appearauce 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 

 Prof. Cope's reference of the coal at this point to the Cretaceous, 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 identifica- 

 tion,*" This point offers, therefore, a more complete continuity in strati- 

 fication and mineral character from the Cretaceous to Tertiary deposits 

 than any other which I have had the opportunity of examining. 



Conclusion. 



Having tra3ed the transition series of the coal-bearing formations of 

 the 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. l^ewberry as based 

 upon the study of the extinct flora. They have, as is well known, pro- 

 nounced this wholeseriesof formations as of Tertiary age, and some of the 

 beds to be as high as Miocene. The material on which this determination 

 is based is abundant, and the latter must be accepted as demonstrated 

 beyond all doubt. I regard the evidence derived from the molluscs 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 flora was cotemporaneous with a Cre- 

 taceous fauna,* establishing an uninterrupted succession 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 

 without extraordinary modification of structure. It is the Binosauria 

 which disappeared from the land, driven out or killed by the more active 

 and intelligent mammal. Herbivorous reptiles like Agathaumas and 

 Cionodon would have little chance of successful competition with beasts 

 like the well-armed Bathmodon and Metalophodon. There is good reason 

 for believing that this iucursion of mammalia came from the South. 



It then appears that the transition series of Hayden is such not only 

 in name but in fact, and that paleontology confirms, in a highly satis- 

 factory manner, his conclusion " already shown many times, that there 

 is no real physical break in the deposition of the sediments between the 

 well marked Cretaceous and Tertiary groups."* 



* Hayden's Annual Report, 1872, p. 541. 



*Th8 circumstance of tlie discovery of a mesozoic Dinosaur, Agathaumas sylvestris, 

 "witL. the cavities of and between his bones stuffed full of leaves of Eocene plants 

 (Leequereaus,) would prove this proposition to be true, had no other fossils of either 

 kind ever been discovered elsewhere. 



* Annual report, 1870, p. 166. For instance, Gral. Surv., Colorado, 1869, p. 197, Dr. 

 Hayden observes, " There is no proof, so far as I have olJ^rvec in all the Western 

 country, of true non-conformitp between the Cretaceous and lower Tertiary beds, and 

 no evidence of any change in sediments or any catastrophe sufficient to account for 

 the sudden and apparently complete destruction of organic life at the close of the 

 cretaceous period." 



