THE SAGE PLAINS OF OREGON 
Frederick V. Coville, 
Botanist of the U. S. Department of Agriculture 
The states of Washington and Oregon are cut in half from 
north to south by a great mountain range known as the Cas- 
cades. B}’’ this climatic barrier the eastern portions of these 
two states are transformed into a great arid plain centering about 
the valley of the Columbia river. The eastern limit of the plain 
is the western base of the Bitterroot mountains toward the north 
and of other ranges belonging to the Rocky mountain s}^stem 
further south. Thus is formed a great wedge-shaped area, its 
base toward the south, where the plains are continuous with 
those of Nevada, and its apex toward the north, where the plain 
is finall}’- shut in by the boreal forest-belt which connects the 
northern end of the Bitterroots with the northern end of the 
Cascades. Near the center of this triangle, in northeastern Ore- 
gon, rises a great, irregular mass of rock known as the Blue 
mountains, Avhich projecting into the ])lain from the eastward 
almost divides it into two portions, the resultant plains area 
being roughly of the shape of a dumb-bell, the u^iper half lying 
in Washington, the lower half in Oregon, and the two connected 
by a narrow neck in the mid-northern portion of the latter state. 
The area is drained largely b}'^ the Columbia river, which has 
cut its*way through the Cascades to the Pacific. In the southern 
portion of Oregon the streams in many ])laces find no outlet to 
oceanic waters, but flow into alkaline lakes and marshy sinks, 
from which their water either percolates into the soil to find an 
outlet elsewhere or is evaporated into the dry atmosphere. In 
altitude the })lains range from less than 500 feet along the Co- 
lumbia river valley to 4,000 and even 5,000 feet in the more dis- 
tant |)ortions. From north to south in a direct line the extreme 
length of the plains is al)Out 450 miles, from east to west in the 
northern portion about 150 and in the southern j>ortion al)out 
250 miles, the relatively narrow neck connecting the two being 
constricted in its narrowest part to not more than 15 miles. 
The first white men to penetrate this region were those he- 
longing to the expedition of Lewis and Clarke, who crossed the 
