Vol. 4] 



Lawson. — Features of the Middle Kern. 



399 



longitudinal valley lying between the scarp and the mountains 

 to the east. In its lower part it has been alluviated, but the 

 alluvium is now dissected by the stream which drains the valley 

 to the Kern. This drainage is by a narrow gorge which lies 

 between the scarp and a mountain spur from the east which 

 separates Havilah Valley from Hot Springs Valley. The exten- 

 sion of the scarp beyond the Kern, if it persists, lies in a rugged 

 country difficult of access and was not pursued further. Beyond 

 the Kern at the point where the drainage from Havilah Valley 

 enters it, Breckenbridge Mountain may have its counterpart in 

 the Greenhorn Mountains, but this ridge is not known to present 

 an abrupt scarp to the east such as exists to the south of the 

 Kern, and it is much more symmetrically dissected with reference 

 to its north and south axis. It would seem probable, therefore, 

 that the Breckenbridge fault dies out about where the Kern 

 river crosses it and that beyond this point the deformation of 

 the region took, in part at least, the form of an arch, the ei'osion 

 of which gave rise to the Greenhorn Mountains. Havilah Valley 

 then may be interpreted as a structural trough, formed at the 

 time of the faulting along the Breckenbridge fault, which has 

 been considerably modified, first by alluviation before its outlet 

 had cut back along the lower part of the trough, and subsequently 

 by stream erosion. But while it appears probable that the Breck- 

 enbridge uplift was continued in part beyond Havilah as an 

 arch, it was also in part extended, as will appear in the sequel, as 

 a fault of more moderate throw to the east of this arch up the 

 canon of the Middle Kern. 



The next point of interest on our route of observation is Hot 

 Springs Valley. This is reached from Havilah by a road which 

 crosses a notch in the mountain spur above referred to. The 

 descent from this divide to the Hot Springs is about 1300 feet 

 and the latter are situated at an altitude of about 2600 feet. This 

 pass over which the road passes from Havilah to Hot Springs 

 Valley is asymmetric in cross profile and has a steep straight wall 

 on the west side which is strongly suggestive of a degraded 

 fault-scarp. 



Hot Springs Valley from Vaughn at its southern end to 

 Isabella at the junction of the South Fork with the Kern Biver 



