158 F. M. ANDERSON 
represented im those of the present, except) asito depths) ‘hie 
canyon of the Klamath had retreated nearly to the drainage of 
the Klamath Lakes, and was possibly separated from it by only 
a low divide. As to the causes which led the drainage of the 
Klamath Lakes from Rogue River to the present outlet, it is not 
quite clear whether it was by the choking of the Rogue River 
outlet by later lavas, or by faulting, or by both combined. To 
the north of the Klamath River there is evidence of considerable 
faulting along the western slope of the Cascades, the upthrow of 
which could have cut off the outlet from the lakes in the direc- 
tion of Rogue River, while in the vicinity of the Klamath no 
great amount of faulting has been observed, but on the contrary 
there is a depression of the Ione and Tuscan deposits. Further- 
more, the Klamath River cuts these deposits in such a manner as 
to harmonize with this view. 
SUMMARY AND CONCLUSIONS. 
The physiographic features of the Klamath Mountains are in 
general those of crossing ranges and intervening structural val- 
leys, modified to a considerable extent by the effects of ordinary 
river erosion. Evidences of an elevated peneplain are unmis- 
takable at an altitude of four or five thousand feet above sea 
level. This peneplain is to be referred in part to degradation 
during the Cretaceous period, and in part to such action during 
the Tertiary. This peneplain has been subjected to disturbances 
ranging in time from inter-Cretaceous to the present. The 
earlier differential movements were those which originated the 
structural features that are conspicuous at present. The later 
movements have developed folds with north and south axes, the 
evidences of which are many. The principal north and south 
fold coincides with the Salmon River range, seen to the west of 
Scott valley, and its continuation on the north and south toward 
the Rogue River Mountains and the Trinity basin. It crosses 
all of the principal rivers of the region in a manner that demon- 
strates its secondary age, which was probably in part compara- 
tively recent. The streams have maintained their westward 
