22 



University of California. 



[Vol.:!. 



The Mohave River crosses the eastern end of Antelope Valley 

 in a comparatively straight course from south to north, and has 

 excavated in the loose gravelly material of the floor of the basin 

 a broad shallow valley (one-half to one mile wide and one 

 hundred to two hundred feet deep), bounded by bluffs, in places 

 abrupt and exposing horizontal beds of gravel, and floored by 

 very fine sandy alluvium. The gravel is splendidly exposed in 

 railway cuttings at mile-posts 19 and 20 south from Barstow. 

 There is about one hundred and twenty feet in thickness of light 

 brown, imperfectly but horizontally stratified, waterworn and 

 water-deposited, moderately fine gravel composed of a great 

 variety of rock species, not showing the localization of the 

 ordinary detrital material but evidently largely derived from the 

 San Bernardino Range about the headwaters of Mohave River. 

 The character of the deposit is clearly alluvial. It is overlaid 

 by a bed cemented by travertine, and this by forty feet of 

 regularly bedded, light red, fine sand and sandy clay. The 

 whole series is tilted very slightly toward the northeast. 



West of the Mohave River Valley, north of Victorville, the 

 gravel plain has little slope and is not dissected to any great 

 distance from the river, as there are no tributaries here owing 

 to the arid conditions; but on the east of the river the same 

 gravel plain rises at an almost abnormally great angle for a 

 detrital slope to the flank of the low range east of the railroad. 

 This resembles a much-eroded detrital slope, but the typically 

 alluvial nature of the material may postulate a slight tilting to 

 the west since deposition. 



In cutting down into this loose Quaternary gravel, Mohave 

 River encountered some spurs from the mountain range on the 

 east and was compelled to excavate through them narrow rock 

 gorges. The principal one, north of Victorville, is about one 

 mile in length and fifty to one hundred feet in depth. It is no 

 wider than the river and has very steep, in places perpendicular, 

 walls. The rock is a hard granite, not easily eroded. The 

 climatic conditions do not favor rapid erosion, but it must be 

 remembered that Mohave River rises in the high San Bernardino 

 Range and flows through this gorge as a perennial stream. At 

 the time of my visit it was at its lowest stage, yet the stream 



