Vol. 6] Baher: Cenozoic History of the Mohave Desert. 341 



Bemnants of a later series occur in Mohave Eiver valley at several 

 points, notably along the railroad about one and one-half miles east of 

 Barstow. The following section, in descending order, of a bluff just 

 north of the railroad, is typical of the series: 



Type-Section of Barstow Series near Barstow 



1. Stratified hard brown material due to arid conditions, but compo- 



sition not determined; persistent stratum over a considerable 

 area 20 ft. 



2. Yellow and light gray silt 4 



3. Stratified fine gravel and sand of dull red color and containing 



red lava fragments 15 



4. Structureless bed of white tuff with angular and subangular frag- 



ments of various other rock species embedded in it 20 



Total 59 ft. 



This formation is extensively developed on the low hills on the north 

 side of the valley between Barstow and Daggett. It is thin, overlies 

 unconformably the earlier series, and remains generally in a horizontal 

 position, but has been extensively eroded. It is a valley formation made 

 under arid conditions. In a small railway cutting near the bluff where the 

 above was taken, this series is locally much broken up and overlaid uncon- 

 formably by 20 feet of the nearly horizontal, roughly stratified, subang- 

 ular gravel and clay which seem to form low Quaternary ridges on the 

 south (pp. 368-370). 



The Rosamond Series was examined in five different localities 

 during the recent reconnaissance. These localities comprise : 

 (1) an area north of Barstow, in Township 11 N, Ranges 1, 2, 

 and 3 W of the San Bernardino Base and Meridian lines; (2) 

 a portion of the Calico Mountains north of the towns of Daggett 

 and Otis, in Townships 10 and 11 N, Range 1 E; (3) Black 

 Mountain, Townships 31 and 32 S, Ranges 44 and 45 E of the 

 Mount Diablo Base and Meridian Line; (4) an area between 

 Rosamond and Mohave in Townships 9 and 10 N, Ranges 12 and 

 13 W, and Township 11 N, Range 12 W of the San Bernardino 

 Base and Meridian lines; and (5) in the region centering about 

 Ricardo postoffice, in Red Rock Canon, on the southern spur of 

 the El Paso Mountains, in Townships 29 and 30 S, Ranges 36 

 and 37 E. In all these localities the series has a general east- 

 west strike. 



In the above localities the Rosamond is mainly a sedimentary 

 series, with only a subordinate amount of both acidic and basic 

 lava flows. The sediments are mainly breccias, with fragments 



