Vol. 6] Baker: Cenozoic History of the Mohave Desert. 363 



very low relief north and south of that town. The present sur- 

 face of the granite north of the Barstow syncline is an even 

 surface of soft, rounded slopes of very little relief (pi. 35b) ; 

 and the same characteristic is exhibited by the granitic areas 

 south of Kramer and between Rogers dry lake and the base of 

 the Rosamond Series north of Rosamond station. 



This old surface can be traced on the crests of the Sierra 

 Nevada and Tehachapi mountains in the vicinity of Tehachapi 

 Pass and on the summits of the latter range northeast of Tejon 

 Pass. 



On a trip to the summit of the San Bernardino Mountains, 

 over that portion of the range mapped on the western half of 

 the San Gorgonio Atlas Sheet, the features of two, and perhaps 

 even three, different cycles of erosion were noted. If there have 

 really been three different cycles there, the middle one should 

 be regarded as only a partial cycle or a sub-cycle, for it was 

 brought to a close in the stage of late maturity or early old age. 

 The summit of the San Bernardino Range is for the six miles 

 of its length, from San Gorgonio to San Bernardino mountains, 

 a long, rather even-crested ridge, which is represented in plate 

 41a. Whether the evenness of this crest is to be attributed to 

 peneplanation, to the uncovering of the uniform upper surface 

 of a batholith or of an old erosion surface which has been 

 formed by streams, is a moot question. The rocks in this ridge 

 do not seem to differ in composition or in erosion-resisting qual- 

 ities from the other rocks of the range. Accordance of summit 

 levels is not a particularly marked feature of the San Bernar- 

 dino Range, although there is a tendency for peaks along the 

 east-west divides, which are the prominent water partings in this 

 portion of the range, to exhibit a sort of accordance which gives 

 the highest summits along a line which runs approximately north 

 and south from the range's highest summit, San Gorgonio 

 Mountain. 



A broad valley, partly filled by a lake, will be noted in the 

 middle ground of plate 41a. A view of the marshy floor of this 

 same valley three miles nearer its source, with the low rounded 

 mountains in the vicinity, is given in plate 41b. This is the 

 valley of Bear Creek, which contains three lakes probably owing 



