NO. 6 PAST CLIMATE OF NORTH POLAR REGION BERRY 



19 



ceived ocean waters from the Pacific or across Eurasia from ancient 

 Tethys, or became ice free during the summer are discussed very 

 briefly in a subsequent section of this paper. 



Fig. 6. — Midsummer isotlierms at the present time. 



SOME PALEOBOTANICAL MISCONCEPTIONS 



Although I have on previous occasions emphasized the lack of 

 climatic value of most of the plant types which i)aleobotanists have 

 relied upon as indicating tropical climates, this subject should not be 

 passed over without some comment in the present connection. 



The principal evidence upon which tropical climates have been pred- 

 icated falls into three somewhat dissimilar categories. First it rests 

 upon tradition which never had any basis. For example the concep- 



