618 



INDEX TO THE STEATIGRAPHY OF NORTH AMERICA. 



overlapping edge of the deposit and believes that the older sediments accumulated 

 farther seaward. He says : " 



The lower portion of the Myrtle as exposed in Oregon corresponds only to the upper part 

 of the Kjaoxville as exposed in California, yet it is quite correct to say that the Myrtle as a 

 whole is the equivalent of the KnoxviUe and Horsetown XShasta) as a whole, if it is admitted 

 that the Myrtle includes beds which are older than any of the Myrtle yet seen in Oregon but 

 which are beheved to form the base of the overlapping strata. These basal beds of the Myrtle 

 presumably occur farther west, beyond the present coast, but they may yet be found in Oregon. 



The age of the Myrtle formation is not yet satisfactorily determined, there 

 being a difference of opinion between Stanton and Knowlton as to the correlation 

 according to the faunas or the floras. The fauna as interpreted by Stanton is 

 of Cretaceous age throughout. The floras as identified by Knowlton comprise a 

 lower flora, of Jurassic age, and an upper flora, of Lower Cretaceous age. 



We quote Knowlton's statement of the problem and the summary of his 

 conclusions : ^"^ 



In November, 1908, Mr. Diller published a paper under the title "Strata containing the 

 Jurassic flora of Oregon,"* the thesis of which he sets forth as foUows: "Two fossil floras have 

 been reported from the Mesozoic rocks of California and Oregon, the one Cretaceous and the 

 other Jurassic. With the former the fauna is Cretaceous, but with the latter the fauna has 

 been regarded as a matter of doubt. It is the purpose of this paper to remove the doubt by 

 showing that in parts of Oregon and California the Jurassic flora * * * is in the 'Myrtle' 

 and Kiioxville beds, while elsewhere it extends down to the horizon of the Mariposa, and the 

 general conclusion is reached that for the Pacific coast the fine between the Cretaceous and the 

 Jurassic is the great unconformity at the base of the KnoxviUe." 



The major portion of Mr. Diller's paper is devoted to proof that the Jurassic flora occurs 

 in the 'KnoxviUe formation — a point conceded by the present writer. It is to the placing of 

 the Jurasso-Cretaceous line at the base of the KnoxviUe that exception is taken. 



Mr. Diller's interpretation of the relations of the several formations concerned in this 

 paper, together with his conclusion regarding the ranges of the floras and the supposedly char- 

 acteristic invertebrates, is shown in the foUowing diagram, which is taken from his paper: 



Shasta flora. 



Lower 

 Cretaceous. 



Jurassic flora. 



Correlation not fully 

 established. 



Paleozoic. 



Jurassic. 



Paleozoic. 



a Personal communication, February 15, 1910. 



>> Bull. Geol. Soc. America, vol. 19, 1908, pp. 367-402. 



