82 WARREN DUPRE SMITH AND EARL L. PACKARD 



accumulation and in part to crustal uplift." This is a great dis- 

 sected plateau. Tertiary sediments in the form of a great syn- 

 clinorium pass under these Tertiary and Pleistocene lavas. 



4. "The Klamath Mountains are the section of the Pacific 

 Border Province adjoining the Cascade Mountains on the west and 

 consisting of relatively old and resistant rocks." The most note- 

 worthy feature of this region is the remarkable peneplain described 

 by Diller. 



5. "The Oregon Lake Section of the Basin-and-Range Province 

 characterized by young block mountains and lake basins." 



6. " The Harney Section is that section of the Columbia Plateau 

 which Hes south of the Blue Mountains." This is largely under- 

 laid by Columbia lava. It is characterized by sage brush, "rim 

 rock," and lacustrine sediments. 



7. '' The Payette Section of the Columbia plateau is the part west 

 of the Snake River Plain, whose substratum consists in large part 

 of lacustrine sediments (applies to northern part only)." This 

 takes in practically all of the upper Snake River drainage. 



8. "The Blue Mountain Section of the Columbia Plateau Prov- 

 ince is the mountainous area entirely surrounded by plateau 

 surface." This section extends up into the northeastern part of the 

 state and includes the Wallowa Mountains, which are in many 

 ways quite different from the Blue Mountains proper. The 

 writers are inclined to make a separate section for this portion. 



9. "The Walla Walla Plateau is that section which lies north 

 of the Blue Mountains." 



This includes most of the DesChutes River basin and that of the 

 famous John Day Valley. This region is noted for its fine wheat 

 lands on the plateau stretches between the rivers and for the classic 

 fossil localities along the John Day. 



The writers suggest the following shghtly simplified subdivisions : 



a) The Columbia-DesChutes Province. 



b) The Willamette Valley Province. ■ 



c) The Coast Province. 



d) The Cascade Plateau Province. 



e) The Klahiath Province. 



/) The Blue-Wallowa Mountain Province. 

 g) The Southeastern Desert Tract. 



i 



