1922] Vaughan: Geology of San Bernardino Mountains 387 



grey and rather persistent except where cut by faulting (pi. 24A). 

 The material is coarse gravel and subangular polygenetic pebbles two 

 inches to a foot in diameter, probably derived from the old rocks to 

 the north. At a distance it might be mistaken for sandstone, but 

 closer examintaion reveals its true character. "While similar to this 

 as regards the general nature of the material, a great part of the 

 fanglomerate at Whitewater Canon shows practically no bedding. 

 About a mile north of Painted Hill there is a great deal of volcanic 

 material present and on weathering the iron colors the rock a deep red. 



Just north of Painted Hill the fanglomerate contains fragments 

 ranging up to more than two feet in diameter. The general appear- 

 ance of the mass is that the fragments are waterworn, but in reality 

 it contains fully as much angular and subangular material. This is 

 unsorted and for the most part displays no evidence of stratification, 

 although there are occasional distinct beds of sandstone. The whole 

 deposit is well consolidated and on the east side of the hill it is firmly 

 cemented. 



The relations of this accumulation to the adjacent rocks are quite 

 clear. North of Painted Hill it overlies the old schists and gneisses. 

 To the east it dips under more recent fanglomerate which differs 

 from it in being more uniform and massive and in lying nearly hori- 

 zontal. Furthermore, the later deposit is of yellowish color as con- 

 trasted to the grey and purplish grey of the Coachella. The latter 

 outcrops on the west side of Mission Creek half a mile below Hog 

 Ranch and also on the south side of the hill south of the Whitewater- 

 Desert road. Here the strata form a low anticline whose axis strikes 

 S 30° E and whose limbs dip about 6°. 



The Coachella fanglomerate is of such nature that it must have 

 been deposited near the base of a mountain mass. It contains many 

 basalt fragments. It is therefore probable that this detritus was 

 deposited after the mountain mass had begun to rise, but probably 

 only shortly after, as there was still considerable basalt available to 

 contribute to it. 



Cahezon fanglomerate. — We have already seen that during the 

 development of the second cycle fanglomerate was deposited in Bear 

 and Holcomb valleys. 



The largest area in Bear Valley is the broad flat between Rathbone 

 Creek and Erwin Lake. The material is almost wholly xuisorted 

 angular and subangular quartzite brought down from Sugarloaf Moun- 

 tain to the southeast. This area once extended farther west, but only 



