56 R. W. Chaney 



clisere, that is, a sequence of climaxes with the corresponding 

 cHmates, such as may be seen today from the foot to the summit 

 of high peaks or from tropical to polar lands. Not only does 

 the fossil plant record of the Cenozoic indicate such a cliseral 

 sequence, but also the evidence of the animals, both invertebrate 

 and vertebrate, and of the sedimentary rocks in which they are 

 enclosed, is in accord with the assumption of this climatic trend 

 through the Cenozoic. It has been discussed on the basis of the 

 plant record in several publications by the writer and his asso- 

 ciates,^' '*'*' °' "■'■ ^ and will not be reviewed here in detail. 



Floras of older Tertiary age, including those referred to the 

 Eocene epoch and some of those referred to the Oligocene,* 

 have been critically studied in western North America from 

 the west flank of the Sierra Nevada in central California, from 

 the western border of the Cascade Range in central Oregon, from 

 the John Day Basin of eastern Oregon, from the Puget Sound 

 area and from the eastern slope of the Cascades in Washington, 

 and from the Kenai Peninsula and adjacent Alaska.f These 

 floras as represented in California and Oregon are made up 

 dominandy of types of plants which have their modern range 

 in the low latitudes of both hemispheres. Silicified stems make 

 up a conspicuous part of the fossil record in the Auriferous 



* Confusion concerning the boundary between these two series of the Tertiary 

 in western North America often makes impossible an exact age designation. The 

 terms "Eocene" and "older Tertiary" as applied to American floras will be used 

 synonymously in this paper, since most of the floras discussed are considered by 

 the writer to be of Eocene age, 



tin addition to the papers listed in the bibliography, the following studies 

 have advanced to the point of completed manuscript or of matured conclusions: 

 C. A. HoUick, on the Tertiary floras of Alaska; R. S. LaMotte and others, on the 

 floras of Washington; R. W. Chaney, on the Clarno flora of eastern Oregon; H. D. 

 MacGinitie, on the older Auriferous Gravels floras of California. 



