FOSSIL FLORA OF THE JOHN DAY BASIN, OREGON. 



Bv F. II. Knowlton. 



INTRODUCTION. 



For a niiiii})er of years I have been gradually accumulating^ material 

 for a thorough revision of the Tertiary floras of the Pacific slope. 

 Fossil plants are known to occur at numerous points within this 

 area, and their study and identification has already furnished valua))le 

 data bearing on the geological history of the region, and when still 

 further exploited it is confidently expected that they will afford more 

 exact data for the use of geologists. This investigation is progressing 

 satisfactorily, and at no distant day it is hoped to have it in form for 

 final pul)lication. 



From time to time various members of the United States Geological 

 Survey, as well as others not connected with this organization, have 

 sent in small collections of fossil plants for determination. These 

 have been studied and reported upon as fully as the condition of the 

 problem permitted, so that the determinations could bo immediately 

 available to geologists, but with the reservation that none of the ques- 

 tions could be full}' settled until all known material had ])een studied 

 and properly correlated. 



The rich fossil plant deposits in the John Day Basin, as set forth 

 more fully in the historical account which follows, have been known 

 for a period of nearly fifty years, ])ut their study has been carried on 

 in a more or less desultory manner. There has also been considerable 

 confusion as to the horizons whence these plants came. As various 

 species of plants described originally from the -lohn Day region were 

 detected in various other localities in Oregon, and in surrounding 

 areas, as central Washington, western Idaho, and northern California, 

 it became more than ever apparent that a thorough study of all 

 material obtainable from this type area would be necessary before any 

 definite or satisfactory conclusions could be reached. 



The immediate incentive for this revision was furnished by the 

 receipt of a considerable collection of plants, made by Dr. John C. 

 Merriam in 1900 while he was in charge of an expedition into this 

 region made under the auspices of the University of California. 



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