138 TREE ANCESTORS 



entire holly, and chestnut oak types, and may really represent 

 varieties of Dryophyllum. 



There are many oaks described from the Eocene period, some 

 undoubted in their identity, and represented by fruits as well as 

 leaves. They occur in the basal Eocene of Belgium, and in the 

 present plains country bordering the Rocky Mountains, which, 

 however had not yet been elevated at the time that they flourished. 

 Later in the Eocene we find oaks especially abundant and wide- 

 spread in far northern lands, at that time marked by milder tem- 

 peratures than prevail at the present time, a time when temperate 

 floras pushed toward the poles and tropical floras invaded the tem- 

 perate zones. Fifteen different oaks, nearly all authentic and of 

 the chestnut or holly oak type are recorded from the late Eocene 

 deposits of western Greenland: 6 are recorded from Alaska: 

 3 from Sachalin Island: 4 or 5 from British Columbia: 1 from 

 Iceland: and 5 from Spitzbergen. 



Oiigocene times, largely unrepresented by plant bearing beds 

 in North America, show numerous oaks in Russia, Germany, France 

 and Italy. Oaks are exceedingly abundant everywhere through- 

 out the northern hemisphere during Miocene times, especially in 

 the humid forested Mediterranean countries and those of our 

 Pacific coast region, in both of which many noble oak forests must 

 have dehghted ancestral squirrels and extinct members of the swine 

 family with their bounty. Thus 33 Miocene oaks have been re- 

 corded from Italy alone, 20 from France, 15 from Switzerland, 12 

 from Hungary and Croatia, 13 from Styria, 10 from Baden, 9 

 from Bohemia, 7 from Spain and Greece. In this country the 

 records include Virginia on the East coast, Oregon and California 

 on the West coast, the two 'last with more than 10 species each. 

 Nevada, Idaho and the Yellowstone Park all furnish their Miocene 

 oaks, and the forested lake shores of the Miocene mountain basin 

 of Florissant in the Colorado Rockies furnish us with a dozen 

 species of oaks along with numerous other plant and insect types 

 preserved in contemporaneous showers of volcanic ashes. 



Phocene times carry on the Miocene forests which were slowly 

 changing. Over 30 oaks have been described from deposits of 



