150 Ff. VM. ANDERSON 
strongly with their drainage canyons. Scott valley, for example, 
lying entirely within the limits of the Klamath Mountains, has 
a nearly level bottom with general dimensions of eight by 
twenty-five miles, into which converges the drainage of more 
than twenty miles radius, yet the outflow from this valley goes 
through a canyon more than twenty miles in length, which is 
almost impracticable for a wagon road to follow. Indeed, in 
some places the walls of the canyon rise precipitously for more 
than a thousand feet. Most of the interior valleys are of this 
type, including the valley of the Hay Fork, Hyampom, Trinity, 
and Hoopa valleys, the Salmon River, the Illinois, and others. 
Deductions —The explanation of this interesting fact is that 
already suggested in a former paragraph. It is evidently a 
result of the cross-folding of the country—that is, to the devel- 
opment of folds transverse to the course of a drainage that had 
already been established. It is not maintained that this north 
and south system is entirely younger than the drainage, for this 
is not true, but it appears to be evident that there has been an 
uplifting of these transverse ranges after the drainage of the 
region had become established. The progress of this move- 
ment was not more rapid than the erosion of the streams in a 
downward and opposite direction. The transverse barriers are 
mainly north and south, or, to be more exact, a few degrees to 
the west of north. 
These observations apply equally to the Trinity River, the 
Salmon River, the Klamath, and Rogue River, and, as has been 
said, to Scott River, the Illinois, and to some of their smaller 
tributaries. 
THE LARGER BASINS. 
The larger basins already outlined probably had their origin 
in the midst of, or prior to, the Cretaceous period. The Rogue 
River basin, while it does not topographically include the valley 
of Shasta River, yet in a geological sense it includes not only 
this, but also the valley of the Klamath Lakes as well. The 
Trinity basin has been already shown to extend from the upper 
Sacramento and to include the larger valleys tributary to the 
