J. LeConte—Old River-beds of California. 177 
features is all that is required here. Whitney shows: 1. that 
there is in California an old river-system entirely different from 
the present river-system; 2. that the old channels were filled 
by detritus, and the detritus covered by lava-streams; 3. that 
the lava flows, completing the filling of the channels, diverted 
the streams and forced them to cut for themselves new chan- 
and the section is across both; while in figure 2 the new 
have cut across the old, and the section is along the old and 
across the new. 
This peculiar relation of the old to the new river-beds does 
not characterize the whole Pacific slope, but only the aurifer- 
ous slate belt of middle California. It is not found in the 
oast Range, nor in the region of the granite axis of the 
I) ii} if 
WH) 
Fig. 1—Section across Table mountain: L, lava; SS, sandstone ;* G, old gravel ; 
river-bed ; SS, slate bed rock; r, present river; g, present grave 
Thinnimnin” 
Alii 
Fig. 2—Lava stream cut through by modern rivers: aa, basalt; bd, volcanic 
ashes; ¢c, Tertiary ; dd, Cretaceous; RR, direction of old river-bed; rr, of 
new river-bed 
Southern California. It seems to be confin 
Slate belt of the western slope of the Sierra from Plumas 
* The material here called sandstone is @ cemented river sand. It is usually 
‘overed with tufa or tufaceous conglomerate and this latter with lava. 
