456 University of California Publications. [Geology 



from Tehachapi Valley by a movement on the fault which estab- 

 lished this scarp. The gap which connects the two valleys over 

 the rock platform is about half a mile wide, and the rock plat- 

 form is with little doubt a surface of stream planation. This 

 suggestion is confirmed by the section afforded by the gorge at 

 the outlet of Brites Valley. Here the base of the alluvium may 

 be seen reposing upon the bedrock surface, and that surface is 

 again a platform which can only be regarded as a product of 

 stream corrasion. It would seem, therefore, that, flanking the 

 southwest scarp of Bear Mountain where it bounds Brites Valley, 

 there is a stream terrace in large part buried by alluvium. It 

 seems a fair hypothesis in the absence of any other suggestion to 

 correlate this stream-cut terrace with the broad terrace already 

 described as occurring in the northwestern portion of Tehachapi 

 Valley; and in this hypothesis we have the farther suggestion 

 that the stream, which evolved the now dislocated and partly 

 buried terrace, floAved out westward through the present site of 

 Brites Valley. 



CUM MINGS VALLEY. 



Cummings Valley lies immediately to the west of the sharp 

 north-south rocky ridge which forms the western boundary of 

 Brites Valley. It lies at a much lower level than Brites Valley, 

 the drop from the one valley to the other being rather precipi- 

 tous. In the northeast part of the valley where the wagon road 

 to Bear Valley leaves the main road through Cummings Valley, 

 the altitude is 4056 feet, or 353 feet below the lowest part of 

 Brites Valley, while in the middle of Cummings Valley the alti- 

 tude is 3924 feet, or 485 feet below Brites Valley. The general 

 contour of the valley is that of a trapezium. Its eastern bound- 

 ary, as already indicated, trends north and south and has a 

 length of about 4 miles. Its southern boundary is the same east- 

 west, degraded fault scarp which bounds Tehachapi and Brites 

 Valleys on the south. This side is also about 4 miles in length. 

 On the northeast, the southwest scarp of Bear Mountain forms 

 its boundary for about 2 miles. The fourth side of the valley 

 is the more or less serrate edge of a mountainous tract which 

 rises to several hundred feet above the level of the valley on 

 the west. The trend of this boundary is north-northeast and its 



