THE PLIOCENE OF EUROPE, ASIA, AND NORTH AMERICA 305 



to the Asiatic-African period of the mammalian hfc of Pikermi and Mt. 

 Lel)eron. The entire geographic history of the epoch extends from the 

 time of the completion of the Swiss Alps to the establishment of the main 

 coast lines of Europe, the last touches being given to these lines in the late 

 Pleistocene and contributing their motlern aspects. The Plio(;ene was 

 marked throughout by continuous volcanic disturbances. The extinctions 

 and disappearances of mammals are in themselves proof of very profound 

 physiographic changes between the close of the Miocene and the first 

 mammaliferous records of the Lower Pliocene, namely, of depression as 

 contrasted with the extreme elevation at the close of the Miocene. 



At the beginning of the epoch, or Plaisancian stage, the Straits of 

 Gibraltar were formed, and communication between the Atlantic and 

 Mediterranean was reestablished. A bay extended into the valley of the 

 Rhone; Italy was submerged except for the Apennines and a part of Sicily.^ 



The Middle Pliocene, or Astian, named from the region of Asti in 

 Piedmont, is also a stage of marine depression which surrounds almost the 

 entire Mediterranean basin, representing in importance as well as in dura- 

 tion the greater part of the Pliocene. The fauna denotes a rather warm 

 sea. Toward the close of the Middle Pliocene the reelevation of the land 

 and retreat of the sea left Italy with practically its present contours. 



Consequently the Upper Pliocene of Italy is represented solely by fresh- 

 water deposits. It is the contemporaneous marine formations of Sicily, 

 however, which give the name ' Sicilian ' to this final Pliocene stage. The 

 peninsula which connected the Balearic Islands, Corsica, and Sardinia with 

 the mainland opened the Mediterranean more largely toward the east. 

 Beyond the ^gean Sea there stretched the great open marine area of the 

 Caspian and Baltic seas. 



Stages 

 3. Sicilian 



Elevation and 

 modern coast 



lines. 



2. Astian 



Closing with 

 elevation. 



1. Plaisancian 

 Maximum 

 depression. 



Formations 

 A marine phase in Sicily. Fresh- 

 water fluvio-lacustrine deposits 

 of northern Italy and Central 

 France. 



Marine deposits in northern Italy 

 (Asti). Freshwater deposits of 

 southern France. 



Depression and marine deposition 

 in northern Italy (Plaisantin), 

 deep depression of the Po and 

 Rhone valleys of southern 

 France. 



Characteristic Faunas 

 Fauna of the upper Val 

 d'Arno and of Olivola 

 in Tuscany; of Perrier 

 and Coupet in central 

 France. 

 Fauna of southern 

 France, Roussillon, of 

 Montpellier (H6- 

 rault); flora of Mexi- 

 micux (Saone valley). 



Lignites of Casino (Tus- 

 cany) ; Autrey in 

 Saone valley. 



> De Lapparout, A., Traite de Geologic, 190G, p. 1633. 



