OLIGOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 185 



there was a lessening of humidity. The occurrence of pahns (Sabal, Cha- 

 mcerops) in the 13altic region indicates a mean annual temperature of at 

 least 18° C. or 64° F., the existing isotherm of southern Spain and Italy. 

 The prevailing forest flora includes palms, sequoias, and numerous other 

 conifers, figs, cinnamons, magnolias, and trees of south temperate forest 

 type. African, Indian, and Australian types become more rare.' 



Cooler Lower Oligocene conditions of the northern coast of Europe are 

 indicated in the rich flora of the amber beds of Konigsberg (55° north), 

 which include pines, spruces, sequoias, cypresses, oaks, chestnuts, beeches, 

 maples, and also the cinnamon; in the main a north temperate flora.- The 

 period in general is marked by the increase of conifers and the spread of decid- 

 uous trees. Along certain lake borders (Aix, Gargas) of southern France 

 the heat and drought during the latter part of the summer were extreme 

 (de Saporta). The climate of the Oligo.cene was thus less uniform; the dif- 

 ference in seasons became more marked. We know nothing of the grasses. 

 The structure of the teeth of the mammals indicates the continued preva- 

 lence of browsing types, and a very small percentage of grazing and grass- 

 eating types.' Forest and swamp-living types are still very numerous. 

 In the Middle Oligocene of central France (Aix) are found conifers, palms 

 (Flabellaria) , and cinnamons.^ 



North America. — Unfortunately there are no leaf -bearing beds of cer- 

 tain Oligocene age ; in fact, we know nothing of the flora of the region of the 

 great plains in Oligocene times. A hint as to the temperature of Dakota 

 is afforded by the discovery by Loomis * of crocodiles in the old river deposits 

 of the Lower White River group, sure indication of south temperate or 

 Floridian conditions of climate. The Kenai beds of Alaska, formerly con- 

 sidered Oligocene, are now referred to the Eocene ^ and possibly Upper 

 Cretaceous." Thus we must depend upon Europe for our knowledge of 

 the North American climate, and the presence in the two countries of so 

 many similar forms of mammals indicates a uniformity of temperature. 



Physiographic Conditions 



Europe. — The abundant localities where Oligocene mammals are found 

 in Europe indicate an undulating country, thickly forested in places, Avith 

 still-water predominating over fluviatile depositions. In contrast with 

 the Eocene, fluvio-marine deposits are rare. Most localities are 'continen- 

 tal,' or in the interior. Exceptions are the fluvio-marine sands of the Fayiim 



' Geikie, A., Textbook of Geology. London, 189.3, p. 991. 



2 Goeppert, Flora des Bernsteins, Vol. I, 1883, Vol. II (Goeppert, Meuge, Conwcntz), 

 1886. 



3 Geikie, A., Textbook of Geology, 1893, p. 990. 



■• Loomis, F. B., Two New River Reptiles from the Titanothere Beds. Amer. Jour. Sci., 

 Dec, 1904, Ser. 4, Vol. XVIII, pp. 427-432. 



^ Knowlton, F. H., Fossil Flora of .\laska. Bull. Gcol. Soc. Amer., Vol. V, 1893, p. 587. 

 * 6 Note by Dr. Hollick, March, 1909. 



