VoL - 4 1 Lawson. — Tchachapi Valley System. 461 



tain slope on the south, part way across the valley. The geo- 

 raorphy of this side of the valley is that due to the normal pro- 

 cess of erosion and presents no suggestion of faulting. The 

 edge of the valley is indented and the slopes above it are mature. 



No stream of importance comes into Bear Valley so that no 

 notable alluvial cone occurs in it as in the other neighboring 

 valleys. But the various streamlets and the general wash from 

 the surrounding mountain slopes have contributed to its infilling 

 and have given it a floor of alluvium except at its west end near 

 its outlet by way of Sycamore Creek to the Great Valley. Here 

 the alluvium which forms the floor of the valley feathers out 

 and there is exposed a rock platform which is the counterpart 

 of that already described near the southwest corner of Cummings 

 Valley. This rock platform passes eastward and southeastward 

 with an almost flat slope beneath the alluvium, and evidently 

 underlies a considerable portion of the valley. It is with little 

 question a remnant of the same system of stream-cut terraces, 

 relics of which have been detected in Tehachapi, Brites, and Cum- 

 mings Valleys. Its original relation to those relics is not clear, 

 but that is not surprising in a region of such acute diastrophic 

 deformation as that with which we have here to deal. In gen- 

 eral, then, Bear Valley may be briefly stated to have originated 

 by the downward tilting of a tract of mature geomorphy on 

 the south, including a stream-cut flood plain, against a dominant 

 fault along the southwest scarp of Bear Mountain ; and that 

 against this fault there was left in the down plunge a slab, or 

 kernbut, which failed to drop as far as the rest and the top of 

 which forms the ridge-bordered terrace on this side of the valley, 

 valley. 



Beyond this rock platform a narrow gorge opens in the moun- 

 tain ridge which bounds the valley on the west and through this 

 the waters of the valley find their escape by a very precipitous 

 descent to the Great Valley 3000 feet below and only 4 miles 

 distant. This gorge in its upper part lies on the line of the sub- 

 sidiary fault scarp and the same suggestion for its development 

 is here made as for the gorge which drains Cummings Valley, 

 viz., that it is due to the headwater erosion of a high grade stream, 

 Sycamore Creek, cutting back in the face of the northwest scarp 



