BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 26, pp. 295-302 AUGUST 17, 1915 



PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



CLOSE OF JUEASSIC AND OPENING OF CPtETACEOTJS TIMK 



IN NORTH AMERICA ' 



BY HENRY FAIRFIELD OSBORN 



(Presented before the Faleontological Society December 30, 1914) 



CONTENTS 



Page 

 First symposium 295 



Subject of second symposium 295 



European Jurassic — Cretaceous division line 296 



Diastl'opliic and paleontologic evidence as basis for determinations 296 



Fauna and flora 298 



Resume of conclusions of paleontologists, geologists, and paleobotanists. . 299 



Character of paleontologic evidence ; 300 



Ptiases of problem, to whom assigned 301 



Summary 302 



First Symposium 



A year ago the Paleontological and the Geological Societies united iu 

 a symposium on T]i}e Close of Cretaceous and Opening of Eocene Time 

 in North America. That symposium brought out very clearly the ^ide 

 differences of opinion and practice now prevailing among American 

 geologists and paleontologists as to the kinds of evidence on which we 

 must chiefly rely in geologic and paleontologic correlation, chiefly as to 

 the relative criteria of earth movements and of paleontology. 



Subject of Second Symposium 



We are now met to discuss the characteristic features of another im- 

 portant period of geologic time, namely, the Jurassic-Cretaceous limits, 

 as they have been defined in Euroi^o. from Avliich, it can not be too 



1 This paper, which was delivered oiiilly aud has since been put in the present written 

 form, is an introduction lo tho symposium on this subject held at the Philadelphia 

 meetings of the two societies December 29-31, 1914. It is the second paleontological 

 .symposium presented l)oforc the two societies in joint session. Manuscript received by 

 tlie Secretary of the Oeologicai Society .Tuly 2, 1915. 



XXII— Bull. Geol. Soc, Am., Vol. 26, 1914 (295) 



