SUMMARY 401 



With this view the paleobotanists are clearly not in agreement. They 

 regard the beds containing the "Jurassic flora of Oregon" as earlier than 

 the Cretaceous which contains the "Shasta flora." It has been phoAvn in 

 this paper that these two floras meet in the Aucella crassicollis zone in 

 the upper part of the Knoxville. The exact line between the two floras, 

 as far as yet known — and it has been the subject of study for some 

 years — is not a distinct faunal line nor distinctly stratigraphic. 



The position of the line between Jurassic and Cretaceous, as that line 

 is defined in Europe and eastern jSTorth America, is perhaps determinable 

 by the evidence of paleontology and paleobotany, but the ultimate basis 

 of classification for the Pacific coast of the United States is tlie great 

 unconformity at the base of the Knoxville (lower "Myrtle") formation. 



Summary 



The "Jurassic flora of Oregon" described by Professors AVard and Fon- 

 taine occurs in the plant beds of Thompson creek and Cow creek near 

 Xichols station. Careful search has Ijcen made at the localities men- 

 tioned, but its associated fauna is still a matter of doubt. 



The same Jurassic flora has been found in tlie "Myrtle formation" 

 closely associated with an upper Knoxville fauna at Elk river, in Oregon, 

 and in the Knoxville at Big Bar and Eattlesnake creek, on the western 

 slope of the Klamath mountains, in California. 



The lower part of the "Myrtle formation" (Knoxville) in Oregon, 

 though generally imaltered, is locally silicified and contains small veins of 

 quartz. 



The Cretaceous flora (Shasta) described by "Ward and Fontaine from 

 the large area of beds along the western side of the Sacramento valley has 

 been increased in number of species and extended in geographic range by 

 the collections recently made, but the flora is still regarded by Doctor 

 Knowlton as Cretaceous and distinct from the Jurassic flora. 



In the Piddles region of Oregon the Cretaceous flora occurs in the 

 "Myrtle formation" and is associated with an upper Knoxville fauna like 

 that found with the Jurassic flora at Elk river. In the Piddles area there 

 has been found also one doubtful specimen of a species belonging to the 

 Jurassic flora of Thompson creek and Elk river, and suggests a possilfle 

 commingling of the two floras. 



In Oregon onl}^ one doubtful specimen of the Jurassic flora has been 

 discovered below the "Myrtle formation." It occurs in the Dothan. But 

 in California, near Oroville, an extensive Jurassic flora has 1)een reported 

 in the Monte de Oro formation, where it is associated with a fauna that 

 is probably Jurassic. 



