34 F. II. Knowlton — Jurassic Flora of Oregon. 



])oint conceded l)j the present writer. It is to the placing of 

 the Jurasso-Cretaceous line at the base of the Knoxville that 

 exception is taken. 



Mr. Diller's interpretation of the relations of the several 

 formations concerned in this paper, together with his conclu- 

 sion i-egarding the ranges of the tioras'and the supposedly char- 

 acteristic invertebrates, is shown in the following diagram, 

 which is taken from his paper (p. 309) : 



1 

 - Shasta flora 



Aucella 

 crassicollis 



"Myrtle" 



Aucella 

 ■piochi 1 



"Myrtle" 



I 





r 







Dothan 



Aucella \ 

 erringtoni 









Galice 



I 



1 



y Jurassic flora 



I Correlation 

 I. not fiiUy ^ 

 ; established 



J J 









Horsetown 







Knoxville 





1 

 Lower 

 Cretaceous 









Franciscan 





(?) 



Jurassic 



Mariposa 



(regarded = 



Monte de Oro) 





Paleozoic 



Paleozoic 



Thesis of this Paper. 

 At variance with the conclusions above set forth, it will be 

 shown in the present paper that the so-called "Jurassic flora of 

 Oregon" is everywhere of true Jurassic age, that it is practi- 

 cally never* found in association with the acknowledged Cre- 

 taceous flora, and finally, that the line between the Jurassic and 

 the Cretaceous of the region is to be drawn through the upper 

 part of the Knoxville and not at its base. 



Localities of thu: Several Plant Beds 



The localities which have afforded the floras are as follows : 



The "Jurassic flora of Oregon" occurs at three points in 



Oregon — (1) Thompson Creek and the vicinity of Buck Peak ; 



(2) near Nichols Station on the Southern Pacific railroad, both 



* The only possible exceptions are a scrap very doubtfully identified from 

 the area near Riddles, Oregon, and a conifer of no stratigraphic value from 

 California. 



