148 F. M. ANDERSON 
general elevation of 1,600 feet along the coast gradually toward 
the interior. Its eastern margin may be seen from the Sacra- 
mento valley, and, as viewed from the railroad, it has somewhat 
the effect of an escarpment that gradually rises toward the 
north. If the level effects of the mountains north of the Trinity 
basin are properly regarded as a peneplain, it is in a sense the 
northward continuation of the one described by Professor Law- 
son, and which rises gradually toward the north as well as toward 
the east. This approach toa peneplaination has been recog- 
nized by Mr. Diller, and correlated with that represented in the 
See HOO" 
Es as es HUGO 
Sea Level 
Fic. 1.—Profile view of the great Salmon mountain fold, south of the Klamath River. 
broad western slope of the Sierra Nevada, which has been 
described as an inclined baselevel, the deformation of which 
took place at a comparatively late epoch. The great north and 
south fold already referred to rises above this level to an altitude 
generally of seven or eight thousand feet, as in like manner do 
also the Siskiyou, the Scott, and the New River ranges. The 
peneplain is distinctly noticeable along the coast in northern 
Humboldt and Del Norte counties, passing into Oregon, where 
it generally has an altitude between two thousand five hundred 
and four thousand feet. 
The valley depresstons.—All\ the larger valleys of the Klamath 
Mountain region are structural valleys. For the most part they 
may be included in two or three systems or basins, the signifi- 
cance of which has not yet been sufficiently recognized. One of 
these systems describes a broad curve across the northern portion 
of the Klamath Mountains, the other crosses them at the south. 
1 Fighth Ann. Rept. U. S. Geol. Surv. 
