

sectio:n" II. 



THE HORIZONTAL RELATIONS OF THE NORTH AMERICAN 

 TERTIARIES WITH THOSE OF EUROPE. 



Uniformity of system requires that an identical scale of stratigraphy 

 be employed by all geologists. In accomplishing this object, the students 

 of distinct regions necessarily rely on paleontology as the guide in making 

 determinations of the relations of strata, since determination by observation 

 of continuity is impossible. 



The progress of the vertebrate paleontology in North America of late 

 years has been such as to permit of comparisons with the extinct faunae of 

 Europe and other continents, which give definiteness to our knowledge of 

 the relations between their geologic periods. Comparisons made by Mor- 

 ton and Leidy had nearly determined the position of some of the eastern 

 Cretaceoiis strata, and those of Leidy had approximately fixed those of the 

 White River beds. Lyell and Conrad early deteimined the positions of the 

 Eastern Tertiaries. My own views as to the European equivalency of our 

 Keuper* and Laramie f were first expressed, and I later established the 

 ages of the Wasatch, J Bridger,|| Loup River,§ and PermianT[ formations in 

 America. A more detailed comparison being very necessary, I visited 

 Europe in 1878 for the purpose of examining the rich collections of verte- 

 brate fossils, and read a general synopsis of results before the Congress of 

 Geologists of Paris of that year. The present section embraces a summary 

 of that paper, with some additional matter.** 



The history of the succession of life upon any one portion of the 

 earth's surface is replete with matter for speculation. It shows us a series 

 of faunte succeeding each other, each of which, in many instances, com- 

 mences without previous announcement in the forms of older periods, and 



'Proceedings Academy Pliila., 18CG, p. 249. 



t Report on U. S. Geol. Surv. Forticlh Parallel, iii, p — . Trausac. American Pliilosophical See. , xiv, 

 1869, pp. 40, 98, 243. 



t Proceedings Amer. Philos. Society, February, 1872. 



II Loc. cit., August, 1872. 



§ Annual Report U. S. Geol. Surv. Terrs. , 187:!, p. 402 ; Proceed. Academy Phila. , 1875, p. 257. 



f American Naturalist, 1878, p. 327 ; Proceedings Amer. Philos. Society, 1878, p. 530. 



* * This synopsis was first published in the Bulletin U. S. Geol. Surv. Terrs., v, p. 33. See Comptes 

 Rendus St^nographiques, Congrfes Internationale de Geologic 1880, p. 144. 



