112 



University of California Publications. 



[Geology 



Kern region. The summit zone is less obvious in its relationship. 

 If it represent a still older erosional surface, as is adopted for 

 the time, it seemingly finds no homologue in the Kern country. 

 Lindgren has noted the presence of a Cretaceous peneplain on the 

 western slopes of the Sierra, and a correlation may be made with 

 this. The summit upland and the high valley zone are not rep- 

 resented on the area mapped. The former appears to be entirely 

 lacking in this portion of the Sierra Nevada ; the latter probably 

 finds its analogue in the high valleys south of Lake Tahoe, of 

 which Faith, Hope and Charity valleys are the best repre- 

 sentatives. 



III. The Fault Zone. 



At the first glance from lower elevations, the Carson region 

 of the Sierra Nevada appears to be entirely an aggregate of 

 granite peaks, whose flanks usually descend precipitously to the 

 level valleys, but at times show gentle rises just above the val- 

 leys. The geomorphy wears the air of extreme youth, with no 

 hint of maturity. It is only after one climbs up the steep sides 

 of the range and suddenly enters a country the geomorphic age 

 of which is plainly evident that there is a realization of the 

 complexity of the geomorphogeny. It has been assumed without 

 first adducing proofs that the geomorphic zone below the plateau, 

 composed of the steep slopes and minor details of the topography, 

 is truly a fault zone. That it is such becomes evident upon slight 

 inspection of the map or field. Faulting is immediately recog- 

 nized by a glance at the old river channel, but the larger part 

 of the zone is in granitic rocks and requires more careful treat- 

 ment. The features of the zone will first be described, and this 

 will be followed by a discussion of their origin. For the present 

 it is sufficient to state that the larger proofs of the fault zone 

 being such, are (1) the lack of adjustment between high plateau, 

 steep slopes, and level valleys; (2) steep, often but slightly 

 notched granite fault-scarps; and (3) stratigraphic evidence 

 from the plateau schist areas, river gravels and lava flows. 



Of all the striking features of the fault zone that of Little 

 Valley, a large, well-developed longitudinal valley, is the most 

 important. This importance is due both to the peculiar trend of 

 the drainage, parallel to the range crest, and to the fact that at 



