246 THE AGE OF MAMMALS 



Physiographic changes in Europe. — The Miocene ^v^tnessefI the begin- 

 ning of the phenomena which resulted in the formation of the great chain 

 of Swiss Alps (Fig. 13, p. 59). At the very beginning of the period the 

 lake basins of the Oligocene were gradually drained off and replaced by 

 great river and flood plain deposits. Thus the initial or Burdigalian stage 

 was just opening when the vast Lake of Beauce was drying up, leaving 

 the calcaires de Beauce and calcaires de Montabuzard, the latter containing 

 the earliest Miocene life.^ Over this were poured the earliest sandy de- 

 posits {sables de Chitenay) of the great Miocene river which traversed the 

 northern portion of France and emptied into the English Channel. These 

 deposits of the sables de VOrleanais are composed of formations of different 

 stages, which together contain the typical Lower Miocene mammalian fauna. 

 Thus the early Miocene life is recorded in 'continental formations.' 



During the Middle Miocene, or Vindobonian stage, there was a re- 

 newed depression of the southern coast of Europe, while at the same time 

 the lacustrine deposits of Sansan, Simorre, and St. Gaudens were laid down 

 in southwestern France, giving us a complete record of Middle Miocene 

 life. The coastal depression in the south was followed in the Upper Mio- 

 cene, or Pontian Stage, by a renewed elevation and the fresh and wide- 

 spread 'continental formations,' which give us a most wonderful picture 

 of the life from the Isle of Samos in the east to that of western Spain, as 

 well as of northern Germany. Thus at the close of the Miocene the south 

 of Europe probably covered a tremendous land area favorable to and con- 

 temporaneous with the remarkable development of cursorial, herbivorous 

 mammals, plains-living types, the climatic conditions being similar to 

 those prevailing in East Africa at the present time.^ Even at this time 

 southern Europe was rather sharply distinguished from northern Europe 

 in flora and fauna, probably on account of increasing desiccation. While 

 at Pikermi (Greece) there were giraffes and antelopes, deer (forest types) 

 were common north of the Alps.^ 



The enormous thickness of certain of the Miocene marine deposits 

 (2,700 m.), and of the more massive freshwater deposits, together with 

 these vast periods of elevation and depression, and the great changes in 

 the mammalian life, combine to give us a realization of the great duration 

 of Miocene time. 



Miocene Life of Europe and America Compared 



The Lower Miocene of Europe is very clearly defined by the sudden 

 appearance of the proboscideans, including both mastodons and dinotheres. 



' Mayet, L., Etude des Mammif^res Miocenes des Sables de I'Orleanais et des Faluns de la 

 Touraine. Ann. Univ. Lyon, n.s., I. Sci. Med., fasc. 24, 1908. 



" Deperet, C, Recherches sur la Succession des Faunesde Vertebres Miocenes de la Vallee 

 du Rhone. Extr. Arch. Mus. Hist. Nat. Lyon, 1, IV, Lyons, 1887, p. 249. 



^ Palacky, J., Die Verbreitung dcr Ungulaten. Zool. Jahrb., Abt. Syst. Geog. Biol., 

 J. W. Spengel in Giessen, Vol. XVIII, No. 2, 1903, p. 339. 



