Cenozoic Floras Around the Northern Pacific 65 



might be expected in view of the length of time involved and the 

 distance covered. It is significant to note that this forest, charac- 

 teristic of the lowlands of Oregon and adjacent states during the 

 Miocene, was present in only slighdy modified form at higher 

 latitudes on both sides of the Pacific during early Tertiary time, 

 and that its high-altitude equivalent may be assumed to have 

 occupied the upper slopes and ridges as far south as California. 

 To a tradition-bound stratigraphic paleontologist, the occurrence 

 of a "Miocene" flora in the uplands of Oregon and California 

 during the Eocene epoch may prove disquieting, and may result 

 in the conclusion, not infrequently expressed, that plant fossils 

 are of litde value as time indicators.* With no denial that homo- 

 taxiality, of both fossil floras and faunas, may be used as a rough 

 basis for synchroneity in the dating of sedimentary formations, 

 the conclusion may be expressed that for any detailed knowl- 

 edge of the age of a fossil occurrence, data concerning latitude, 

 altitude, and position with relation to ocean basins are essential. 

 For the equally important considerations relating to the distri- 

 bution and physical indications of the life of the past, such data 

 are obviously required. 



In this connection it seems desirable to quote a statement 

 written in 1879 by J. S. Gardner." This statement was not read 

 by the present writer until after the preceding discussion in this 

 paper had been completed. It indicates the early recognition by 

 paleobotanists of the need for knowing something about the 

 geographic occurrence of a fossil flora before its age can be de- 

 termined : 



The nearly unbroken sequence seen in the Eocene floras extends 



• It should be borne in mind, however, that because of its remoteness from 

 sites of deposition, this upland flora with Miocene characteristics did not enter 

 the record during the Eocene epoch. The critical feature in stratigraphic dating 

 is not the time of existence of a flora or fauna, but the time of its entrance into the 

 sedimentary record. 



