THE OAK AND CHESTNUT 137 



chemical years. The tree is a native of Asia Minor and Syria, 

 Aleppo being the chief exporting point. 



Oak wood is distinguished by a feature that it shares with the 

 beech, in that in both there are large compound rays running 

 radially through the wood in addition to the small secondary rays, 

 and it is these large rays that give the so-called silver grain to 

 oak wood. 



The oaks appear to have diverged from the ancestral Dryophyl- 

 lum stock at the dawn of the Upper Cretaceous, or perhaps in the 

 closing days of the Lower Cretaceous. Some hundreds of kinds 

 of fossil oak leaves have been described, but a considerable num- 

 ber of these, and especially those from the earher rocks are more 

 or less open to suspicion regarding their proper identification. 

 Cretaceous oaks have been described from both Austraha and New 

 Zealand, and Tertiary oaks from Australia and Tasmania by 

 Ettingshausen, but that acute botanist was obsessed with the 

 absolute cosmopolitanism of the Tertiary floras, and most, if not 

 all, of his oak determinations are not to be rehed upon. I do not 

 deny the possibility that oaks may have formed a part of that 

 ancient flora which appears to have spread southeastward from 

 Asia during Cretaceous times, but the proof of this must await 

 more convincing evidence than has as yet come to light. 



Similarly, only 4 of the 14 species of oaks that Heer described 

 from the Cretaceous rocks of western Greenland appear to be true 

 oaks. A large number, 20 in all, of equally dubious oaks have 

 been described from the Dakota sandstone of our western states — 

 this sandstone representing the initial deposits of the advancing 

 Upper Cretaceous sea in that region. Next in point of numbers 

 are the 16 species of supposed oaks described from somewhat later 

 Upper Cretaceous deposits in Westphalia. Other Cretaceous oaks 

 have been recorded from Silesia, Prussia, Saxony and Bohemia in 

 Europe; from Alaska and Vancouver Island on this continent; and 

 from aU sections of the United States where rocks of this age are 

 known, to a much larger extent in the West than in the Atlantic 

 Coastal Plain. No characteristic fruits have been found with these 

 early oak-like leaves, wliich, if they are true oaks, belong to the 



