OF WESTERN NORTH AMERICA. 



67 



UPPER OLIGOCENE, SECOND PHASE (EUROPE, ETAGE AQUITANIEN). 



11. MIDDLE PART OF JOHN DAY FORMATION; DICERATHERIUM ZONE (ALSO 

 UPPER PART OF JOHN DAY, TRANSITIONAL). 



(Figs. 1, 10, 11; PL I). 



HOMOTAXIS AND SYNONYMY. 



America. — 1, Middle part of the John Day formation of Oregon. 

 2, Diceratherium zone of Wortman (500 to 1,000 feet). 



Europe. — Aquitanien. Homotaxis with the Aquitanien of France 

 (typified by the St. Gerand-le-Puy, Allier) is close, as indicated by 



Columbia River lava 

 (basa/t flow, 2000 feet) 



Forest on top of ashes 



ProTTierycochcems zone 

 (loi>vest leyel) 



C< \ '> (-^ R pi y oTiUcTTow' 



250- 

 300' 



E3^e5^ DiceratherivLTTi 

 zone 

 (fossils, numerous) 



Remains of 

 forest in the 

 tuff deposits 



Dicera theritnae. 



.CLARNO' 



Xeocene V ^// ^// 

 ///////////A 



CHICO/ 

 CRETACEOUS' 



/// / / / // // 



^lotherium, 

 ? Oreodon 



(fossils, scarce) 



Fig. 11.— Columnar section of the John Day formation (Oregon), based on studies by Merriam and 



Sinclair. 



similar stages in the evolution of Perissodactyla-Tapiridae, Dicera- 

 theriinse, Aceratheriinse, Chalicotheriidse, and other families. 



FAUNA.^ 



The evolution stages in members of this typical Mountain fauna of 

 the middle part of the John Day are in some families (e. g., Equidse, 



a Merriam, J , C, op. cit. 



h Full John Dny lists were kindly prepared for this paper by Dr. Vv illiam J. Sinclair from Professor 

 Merriam's and his own personal notes. (See also Appendix, p. 91.) 



