2JO 



University of California. 



[Vol. 2. 



Quaternary 



•312 

 •312 

 3i3 

 313 



Terraces 



Canon Cutting 

 Ash Beds 



INTRODUCTION. 



During the summer seasons of 1899 and 1900, the writer 

 traveled over a considerable part of the John Day basin, while 

 in charge of palaeontological expeditions sent out from the 

 University of California to collect vertebrate fossils. The following 

 discussion of the geology contains the results of observations made 

 while engaged in that work. 



Though the object of the expeditions was the acquisition of 

 specimens, much of the value of the material being dependent on 

 the circumstances of its occurrence, efforts were made from the 

 beginning to determine, as accurately as possible, the stratigraphic 

 relations of the fossil-bearing beds. 



In looking over the literature bearing upon John Day geology, 

 before visiting the field, the writer was considerably surprised to 

 find that only a few short paragraphs relating to the subject had 

 ever been published, and that in many of the most important 

 particulars these accounts were decidedly contradictory. 



In view of the disagreement among observers regarding the 

 geological history of the region, it was perhaps to be expected that 

 no single account would be found to agree with the facts. The 

 first season's work in the field demonstrated that this was actually 

 the case, and showed the necessity of working out the true strati- 

 graphic succession as an indispensable preliminary to satisfactory 

 palaeontological work. With this object in view, as much informa- 

 tion was gathered as could be obtained without interfering seriously 

 with the main work of the expeditions. 



Future investigations will certainly show that very many 

 important things have been overlooked, and doubtless many weak- 

 nesses in the present discussion will be pointed out ; the writer's 

 purpose will, however, be accomplished if the general stratigraphic 

 succession and the sequence of major geological events are here set 

 forth in such a manner as to make intelligible discussions of the 



