114 F- H. KNOW ETON 



ica, that is, cool temperate. This flora, which is closely similar to 

 that in north Greenland and the valley of the Mackenzie River, 

 undoubtedly approached from the north. The presence of palms, 

 which are found in the lower parts of the formation, argues, on the 

 basis of present distribution, a somewhat warmer climate, just as the 

 numerous thick beds of lignite throughout the formation argue for 

 extensive, long-continued, moister, marsh conditions. 



The flora of the lower member of the Fort Union as at present 

 elaborated embraces about eighty-five species of which number about 

 sixty-five are found in the upper member, while only sixteen of the 

 eighty-five species are found in the Cretaceous below. The uncom- 

 formity of the base of these beds together with the differences in the 

 flora, clearly and logically marks the point at which the line is to 

 be drawn between Cretaceous and Tertiary. 



In the Mississippian region in Louisiana and Mississippi we have 

 a small Eocene flora (Eolignitic) comprising palms, evergreen oaks, 

 magnolias, laurels, cinnamomums, etc., which appear to be most 

 closely affiliated with small floras in northern New Mexico and adja- 

 cent Colorado, the latter in turn being most closely related to much 

 larger post-Laramie floras in the Denver Basin of Colorado. These 

 embrace the Arapahoe with about thirty species, and the Denver with 

 nearly two hundred species, and are believed to be slightly older than 

 the Fort Union — in any event, there are only about thirty species 

 in common. 



The Green River formation of upper Eocene age occupies a quite 

 extensive area in central and western Wyoming, and has afforded a 

 flora of some eighty species. It is very distinct from the Fort Union 

 and other Lower Eocene floras, and shows a distinct increase of 

 modern forms. 



In the northern Pacific coast region there are a number of Eocene 

 floras, among them that of the Swauk which occurs just east of the 

 Cascade Mountains in Washington. This large flora is entirely 

 different from any other in this country, and consists of types that are 

 for the most part found in Central and northern South America, 

 among them being palms 6 feet in diameter and in layers sometimes 

 a foot in thickness. This shows that the palms were not sporadic 

 or occasional, and indicates, as do many of the other things, that the 



