MESOZOIC AND TERTIARY FLORAS 115 



climate was mild, probably subtropical. The overlying Roslin for- 

 mation contains a flora that is almost entirely different from that of the 

 Swauk, and lacking the presence of palms was probably slightly 

 cooler than the underlying formation. 



To the northward and covering a vast area in Alaska and well out 

 on the Alaskan peninsula is the Upper Eocene Kenai formation which 

 has afforded a rich flora of oaks, poplars, willows, hazels, walnuts, 

 magnolias, horse-chestnuts, and maples, together with pines, spruces, 

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

 abundantly in Greenland, Iceland, and Spitzbergen, showing that it 

 was of wide extent in similar northern latitudes. It is distinctly a 

 warm-temperate flora. Another Upper Eocene flora is found in the 

 Clarno formation of the John Day Basin, Oregon, and in the Payette 

 formation of western Idaho. It embraces walnuts, hazels, birches, 

 alders, oaks, elms, sycamores, maples, ashes, etc., and is temperate 

 or warm temperate, in character. 



Eocene floras in the Atlantic area are of very little importance as 

 thus far developed. 



Miocene.- — The Miocene flora of North America is relatively not 

 a large one although it comprises probably five hundred species as 

 now known. The deposits occur often in isolated basins, widely 

 separated, and there is usually comparatively little in common between 

 them. A number of the more important areas may be briefly 

 mentioned. 



At Brandon, Vermont, in the midst of ancient crystalline rocks, 

 occur small pocket-like deposits of lignite which have yielded large 

 numbers of fossil fruits and a very few poorly preserved leaves. The 

 fruits have been studied by Lesquereux, Perkins, and others, and 

 about one hundred and fifty nominal species described belonging to 

 the genera Nyssa, Hicoria, Juglans, Bicarpellites, Cucumites, Tri- 

 carpellites, etc. 



At Florissant, Colorado, also in the midst of older rocks, there are 

 small lake-bed deposits which have afforded vast quantities of plant 

 and insect material in an admirable state of preservation. The 

 plants number upward of two hundred species, among them being a 

 great number of very modern types and even including not a few 

 herbaceous forms. This flora as a whole is very unlike anything 



