400 



J. S. DILLER THE JURASSIC FLORA OF OREGON 



sic the world over, while that of the upper part of the Knoxville contains 

 an equally characteristic array of Cretaceous forms." 



-Vertical Eange of Aucella and the two Floeas in California 



AND Oregon 



lu the accompanying diagram (page 369) is shown graphically the 

 vertical range of the various forms of Aucella as Avell as the Shasta and 

 Jurassic floras applied to the Oregon section. The "]\Iyrtle formation" 

 corresponds to the Shasta series, and the Galice formation probably corre- 

 sponds to the Mariposa slates. These are separated by the Dothan for- 

 mation," which is conformable to the Galice, but unconformable to the 

 overlying "]\l3'rtle/' and probably corresponds to the Franciscan of Cali- 

 fornia. Aucella erringtoni characterizes the Galice and Dothan, which 

 are conformable. Aucella piochi and A. crassicolUs belong to the "Myr- 

 tle," which, appears to be a conformable series throughout. The "Myrtle" 

 and the Dothan are unconformable and the imconformity marks the final 

 great folding of the Sierra Nevada. 



The earliest Jurassic flora of Oregon occurs in the Mariposa (Monte 

 de Oro), the equivalent of which in Oregon, judging not only from its 

 lithology and fauna, but also from its associated volcanic rocks, is the 

 Galice. A trace of the Jurassic flora I have reported from the Dothan, 

 Init a large part of it occurs in the "j\Iyrtle," extending well up into the 

 horizon of Aucella crassicolUs. 



The Shasta flora of the upper part of the "M}Ttle" occurs throughout 

 the Horsetown horizon and locally the greater part, if not the whole, of 

 the horizon of Aucella crassicolUs of the Knoxville. The two floras are 

 marked in the diagram (page 369) as overlapping. They have not yet 

 been found associated, but their geographic distribution and faunal rela- 

 tions strongly suggest such a possibility. 



Limit between the Jurassic and Cretaceous 



The close of the Jurassic on the Pacific coast has generally been re- 

 garded as marked by the great deformation and uplift that finally added 

 the Sierra Nevada to the continent — a deformation marked by the un- 

 conformity Ijetween the "Myrtle" and the Dothan. This limit is an im- 

 portant structural feature and corresponds generally to the paleontolo- 

 gist's interpretation of the fauna, the Mariposa being Jurassic and the 

 Knoxville Lower Cretaceous. 



1' American Jourpal of Science, vol. xxiii, June, 1907, pp. 401-421. 



