152 TREE ANCESTORS 



same age on Sachalin Island. They were also present at that time 

 in Grinnell Land, Iceland and Spitzbcrgen. 



As usual with all tree histories the Oligocene records show a fall- 

 ing off in abundance and variety of elms, only 4 being known 

 from rocks of that age and these being confmed to the European 

 area, where they are found in France, Italy, Germany and Styria. 

 If the Oligocene record is poor that of the succeeding Miocene rocks 

 fully make up for this paucity of records for the closing days of the 

 older Tertiary, for we know over 30 Miocene species of elms, and 

 they were very abundant at many localities, particularly in Europe. 

 Elms must have been a prominent element in the Miocene forests 

 of Europe for their remains occur in rocks of that age in the follow- 

 ing countries: France, Switzerland, Italy, Germany, Bohemia, 

 Silesia, Styria, Carinthia, Croatia, Gahcia, Austria, Hungary, 

 Transylvania and the Caucasus. In Asia 3 species have been 

 found in the late Miocene of Japan. In North America they 

 occur on both the east and west coasts and in the interior, being 

 knouTi from Maryland, Virginia, Florida, Mississippi, Colorado, 

 Oregon and California. They were not uncommon at that time in 

 the basin in which lay the Miocene Lake Florissant in the Colorado 

 Rockies, and their occurrence in the early Miocene deposits of 

 Florida and Mississippi is especially interesting because there they 

 were associated with breadfruit, palms, and other warm climate 

 types of trees. 



The Miocene probably witnessed the maximum distribution of 

 the elms, for at that time they flourished in regions from which 

 they are absent in modem times. During the succeeding Pliocene 

 about a score of species of elms contributed to the geological record. 

 They were especially abundant in southern Europe, in Spain, 

 France, Italy, Germany, Styria and Slavonia. They were repre- 

 sented in the Pliocene deposits of Asia Minor, and the far east had 

 its species in Japan. American records are as usual for the PHo- 

 cene, scanty, but two elms of that age are known from southern 

 New Jersey. 



Pleistocene climatic changes and the glaciation of that time un- 

 doubtedly played their parts in bringing about the modem dis- 



