386 University of California Publications in Geology [Vol. 13 



present height, but whether before the beginning of the uplift or after 

 the second cycle or one of the subcycles is an open question. The over- 

 lying fanglomerate is similar to that being deposited at the present 

 time and therefore must have been laid down after the uplift. 



The basalt disappears about a mile northwest of Old Woman 

 Springs, but the bench, though inconspicuous, continues for nearly 

 two miles farther. It consists of desert deposits: playa silts, some- 

 what calcareous and gypsiferous, and fanglomerate. The extent of 

 these beds is not known, but they are found in several places to the 

 west, where the small washes cut down through the more recent fan- 

 glomerate. Two miles west of Box S Springs sediments are exposed 

 which are lithologically identical to those described above. These beds 

 were evidently laid down under conditions similar to those existing in 

 the desert today, and must have been deposited before the mountains 

 to the south reached their present elevation, but it is impossible to say 

 just how long before. 



Coachella fanglomerate. — On the east side of Whitewater Canon, 

 from Painted Hill four miles northward, there is a clastic rock having 

 all the characteristics of a fanglomerate. For the most part the frag- 

 ments are angular and show but little sorting; though the material 

 seems to vary somewhat throughout the mass. Along the crest of the 

 ridge the strata dip 20° to 40° eastward, but flatten somewhat toward 

 the east. 



Opposite Red Dome the fanglomerate consists mostly of sharply 

 angular fragments varying in size up to three feet across. By far 

 the largest part of this is porphyry, but other rocks, granite and 

 basalt, are also present. Some strata contain sufficient volcanic mate- 

 rial to color them red and give them the appearance of flows some- 

 what shattered, but the presence of other rocks shows their fragmental 

 character. Some rather large boulders are present, one porphyry 

 block being more than eight feet across and a block of basalt six feet 

 across. Some of the finer material is so broken down as to resemble 

 soil. This particular mass differs somewhat from that to the south- 

 east in its coarseness, extreme angularity, and high basalt content ; 

 but such differences are to be expected in deposits of this sort even 

 within short distances. It is not certain whether they represent differ- 

 ent horizons which have been faulted into juxtaposition or local vari- 

 ations of the same formation. 



The fanglomerate as seen two miles southeast of Red Dome is 

 typical of the greater part of the mass. The strata are light and dark 



