Vol. 4] 



Lawson. — Tehachapi Valley System,. 



455 



be referred to as the southwest scarp of Bear Mountain. The 

 western boundary of the valley is a sharp low ridge with north 

 and south trend which spans the space betwen the two converg- 

 ing scarps above noted. This ridge is composed largely of crystal- 

 line schists, the strike of which is north and south with the trend 

 of the ridge. The ridge separates Brites Valley from a larger 

 valley on the west known as Cummings Valley, which lies at a 

 much lower level. At the southeast end of the valley a mountain 

 stream comes in from a gorge in the southern scarp. This stream 

 has built up an alluvial fan which is co-extensive with the limits 

 of the valley. The floor of the latter is the surface of this fan 

 and its general slope is down toward the northwest end of the 

 valley, where the outflowing waters have cut a gorge down 

 through the edge of the fan and deep into the underlying bed- 

 rock, and so find their way to Cummings Valley. Along the base 

 of the southwest scarp of Bear Mountain, the debris from the 

 degradation of the scarp interdigitates with the edge of the fan 

 and being locally dominant reverses the slope. 



The gap through which one enters Brites Valley from 

 Tehachapi is a platform of bedrock or flat-topped ridge between 

 the two valleys. But over this ridge some of the alluvium from 

 the fan which fills Brites Valley has spilled into Tehachapi 

 Valley. A terrace-like shoulder on the south side of this flat- 

 topped rocky barrier, where it is crossed by the wagon road is 

 544* feet above Tehachapi station. The lowest part of the 

 gap is about 500 feet above Tehachapi station. The floor of 

 Brites Valley at the farm house at its west side, just before 

 entei'ing upon the descent to Cummings Valley, is 446 feet 

 above Tehachapi station. From these figures it will be appar- 

 ent that Brites Valley is on epiite a different level from 

 Tehachapi Valley, a fact, which, considering their immediate 

 juxtaposition and open connection, can only be explained on 

 the hypothesis of their diastrophic origin. The eastern edge of 

 the rocky platform which separates the valleys is in direct line 

 with the western scarp of Bear Mountain and we have in this 

 fact a pointed suggestion that Brites Valley has been dislocated 



* This and other altitudes were determined, where not otherwise stated, 

 by means of a mercurial barometer, using Tehachapi station, elevation 3963 

 feet, as a base. 



