MliRRIAM.J 



John Day Basin. 



30.3 



The flora of the John Day was unknown until the summer of 

 1900, when a small collection of leaves was obtained by the Uni- 

 versity of California party from the upper beds near Lone Rock. 

 These specimens were examined by Professor Knowlton, who 

 reports upon them as follows: — 



"Three and one-half miles south of Lone Rock [locality 861]. 



Sequoia laugsdo7'fii (Brgt.) Heer. 



Juglans n. sp. 



Salix sp. 



Phyllites n. sp. 



Fragments. 



"The locality south of Lone Rock [loc. 861] is represented 

 by a single known species. It is impossible to settle the age from 

 these data, but judging from the affinities of certain of the mew 

 forms detected this horizon is possibly not far from that of the 

 Van Horn's ranch* material. Much larger collections must be 

 made before the age can be satisfactorily determined by the 

 plants." 



COLUMBIA LAVA. 



The name given to the lava formation above the John Day was 

 first used by I. C. Russell f, who applied it to the series of eruptives 

 which forms such a prominent feature of the geology in the area 

 drained by the Columbia River. In the region discussed by 

 Russell there are several distinct horizons of Columbia lava, sepa- 

 rated by important formations belonging to different geological 

 periods. Obviously only one of them can retain the name, if it is 

 to be used as a series or formation name in geological classification. 

 This one should be the horizon which is most prominent along the 

 Columbia River, as it was this formation which suggested the name. 

 In the John Day basin it is found that the lavas of the Columbia 

 form a well-defined series which lies between the John Day and 

 the Mascall formations. Other eruptives in this region are hardly 

 to be confused with it. This series is, moreover, that one of the 

 several to which the name is applied which has the greatest lateral 



*Mascall formation. 



f Bull. No. ro8 U. S. Geol. Survey, p. 20. 



