532 F. H. KXOWLTOX EVOLUTION OF GEOLOGIC CLIMATES 



flora that is almost entirely different from that of the Swank and, 

 lacking the presence of palms, was apparently slightly cooler than tho 

 temperature obtaining during the deposition of the underlying beds. 



At Cherry Creek, Oregon, there occurs a small lower Eocene flora of 

 '20 species in beds of the lower part of the Clarno formation. It is a 

 warm temperate flora. Almost the only known middle Eocene flora 

 found on this continent is that of the Green Eiver formation of western 

 AVyoming. It has a flora of about 80 species, mainly of very modern 

 types, among them such as Acrostichium, Lygodium, Mannicaria, 

 Musophyllum, Sapindus, Zizyphus, etcetera, which indicate a climate 

 considerably warmer than the Eort Union, for instance. 



Another small flora of approximate middle Eocene age is the Claiborne 

 flora of Georgia recently elaborated by Berry.^^ It comprises only 17 

 species, but embraces such a proportion of absolutely determined forms 

 that there is believed to be little probability of error in interpreting their 

 requirements. It is distinctly a coast or strand assemblage, and Berry 

 concludes that it indicates a condition approximated by the subtropical 

 or warm temperate rain forests of the present day. Being in proximity 

 to the warm Eocene ocean currents, it must have been uniformly humid, 

 and the temperature ''would have to be uniform rather than hot, . . . 

 for any degree of Avinter cold would have been fatal.'' 



In Alaska we have the upper Eocene Kenai formation, which has 

 afforded a rich flora of oaks, poplars, willows, hazels, walnuts, magno- 

 lias, horse-chestnuts, and maples, together with pines, spruces, cedars, 

 and sequoias. This flora is also found in British Columbia, and is 

 abundantly represented in Greenland, Iceland, and Spitsbergen, show- 

 ing that it was of wide extent in northern latitudes. It is distinctly a 

 warm temperate flora. 



Turning now to the Old "World, we find a number of important Eocene 

 floras, though not all have yet been worked up to the point where their 

 data can be made full use of in interpreting climatic conditions. Thus, 

 the basal Eocene, the so-called Paleocene of Schimper, or the Montian 

 and Thanetian stages of subsequent writers contains two importart 

 floras in northern France and Belgium. That of the plastic clays of 

 Trieu de Leval (Hinaut), Belgium, as described by Marty, com^prises 

 only about 20 species and is thought to find its closest resemblance in 

 the equatorial region of South America. The flora from the travertines 

 of Seganne, France, elaborated by Saporta, is larger (87 species) and is 

 ap]>arently a tem]3erate or warm temperate flora. 



-^ E. W. Berry : V. S. Geol. Survey Trof. Paper 94. 1914. p. 129. 



