Hbrshey.] Quaternary of Southern California. 



21 



Gently sloping plains of granite debris meet near the center, 

 where there is a distinct but slight depression. About five miles 

 east of Kramer the broad basin becomes decidedly rolling but 

 not hilly, and in the central depression are evidences of stream 

 action such as low bluffs and dry waterways. Everywhere the 

 detrital slopes are more or less distinctly stratified and part 

 of the material is clearly waterworn. It is not as perfectly 

 stratified nor as as well waterworn nor horizontally disposed as 

 an alluvial deposit in a humid region, nor yet is it as free from 

 evidences of the action of water as an ordinary talus or the soil 

 on our mountain slopes. 1 can unreservedly accept the theory 

 lately applied by Professor N. S. Shaler in explanation of 

 similar detrital slopes in the Cordillerau region,* namely, that 

 the material is brought from the mountain sides and gulches 

 by torrential floods caused by "cloud-bursts," the form of 

 precipitation so characteristic of desert regions, and accumulates 

 on the near-by plains because there are no perennial trunk 

 streams to slowly carry it away into the depressions. 



From a point near Daggett to about five miles west of 

 Barstow the old Mohave River Valley, lying south of the present 

 valley, is obstructed by a broad, low ridge of a uniform light 

 brown color and smooth topography except for many small 

 shallow ravines. It is apparently an old detrital slope of 

 late Quaternary age which has been disturbed and extensively 

 eroded, At four miles west of Barstow it was found to be 

 composed of angular and sub-angular debris of many kinds 

 of rocks, including various old crystallines, basic lavas, and 

 limestone. This deposit extends up the Mohave River Valley on 

 the southeast side of the Santa Fe railway for many miles, and 

 between mile-posts 10 and 16 south from Barstow it has clearly 

 the form of a detrital slope, much eroded, but in many places 

 retaining its even but sloping surface. It merges into a gravel 

 deposit, to be described later. A long, even detrital slope of 

 later age bounds the low ridge on the valley side near Daggett 

 and Nebo stations. This has been eroded into a very low 

 bluff or bank by Mohave River, and the present broad, sandy 

 flood-plain lies lower. 



*Bull. Geol. Soc. Amer.. vol 12, pp. 285-286. 



