6 EDWARD W. BERRY 



although they must have been abundant since they again appear 

 in the North American fossil record after the close of the Oli- 

 gocene. Two or three species of Platanus of Oligocene age have, 

 however, been discovered in European plant beds. 



The Oligocene period was followed by the Miocene, a period 

 during the early part of which the Oligocene elevation culmmated 

 and subsidence set in. This was accompanied by a striking 

 climatic change, at least in the Eastern United States. In our 

 southern states the Oligocene faunas and floras were such as 

 flourish today under the equator. The succeeding Miocene de- 

 posits which overlie them in Northern Florida and elsewhere con- 

 tain leaves of trees of the temperate zone and the remains of a 

 marine fauna which had advanced from the New Jersey-Maryland 

 region as the tropical fauna was driven southward. North Amer- 

 ica does not contain very many Miocene plant beds but neverthe- 

 less the remains of plane trees have been collected from Oregon 

 and California on the Pacific coast, from the Yellowstone Park, 

 and from Virginia on the Atlantic Coast. In Europe where Mio- 

 cene plant beds are more frequent the leaves of Platanus are abun- 

 dant and widely distributed although they belong to but few 

 species — five have been described. One of these, Platanus ace- 

 roides, first described by Goeppert in 1852, is the dominant 

 Miocene form of the whole northern hemisphere. Its European 

 records include Baden, Switzerland, Silesia, Italy and many local- 

 ities in Austria Hungary — a region remarkably rich in plant bear- 

 ing deposits of Tertiary age. 



Succeeding the Miocene are the deposits of the Pliocene lakes, 

 rivers and seas. The Pliocene is the youngest period of the Ter- 

 tiary age. North America was of much the same geographical 

 extent as it is today and fossil plants are almost entirely unknown, 

 consequently although the plane trees were unquestionably present 

 they have left no records. Europe on the other hand was a region 

 of great geographical change and mountain-making. The chief 

 of these changes centered about the Mediterranean sea, the center 

 of the classical world. At one time its waters withdrew westward 

 to Italy leaving behind a chain of lakes. A wide grassy plain 

 occupied the present Aegean region, another broad land bridge 



