1922] Vaughan: Geology of San Bernardino Mountains 



where Arrastre Creek enters the valley the distance across the strike 

 of the limestone is 4700 feet and the dip about 60° to the southwest. 

 As calculated from these figures the limestone is 4300 feet thick 

 (fig. 3). In neither of these two cases do we find the bottom of the 

 limestone definitely limited, and 4500 feet is therefore a conservative 

 estimate of its total thickness. 



Saragassa quartzite. — The relation of the Saragossa quartzite to 

 the Furnace limestone is clearly seen in a section a mile northeast 

 of Doble, where both are found dipping 20° to the southwest. The 

 limestone grades up into a soft decomposed biotite schist about 50 feet 





t N 



"ft. „ 





Quartzite/^ 







'■/ / t* / ; t ; t / J J 



/ • / * * y f fi i / 



//Limestone y / // / i 



vM\Q-ranitevT /j 



a a' 



Fig. 3. Section south of Smart 's Kancli. 



thick, and then comes 120 feet of white and pink quartzite so recrys- 

 tallized as to have lost all semblance of its original elastic structure. 

 This is overlain by several feet of quartzite pebble conglomerate. The 

 pebbles vary in size from half an inch to an inch in diameter and are 

 usually well rounded. They are imbedded in a coarse schistose matrix 

 containing considerable muscovite and some biotite. 



The pebble conglomerate is overlain by 200 feet of schists. The 

 bedding is rather thin, from a fraction of an inch up to a foot, and 

 the material varies from fine biotite schist to coarse, gritty quartz- 

 biotite schist. Toward the top it becomes free of dark constituents 

 and finally grades into sacchroidal quartzite. The details of some of 

 the bedding are important in showing the true sequence of deposition ; 

 for the mass as a whole has been so tilted here and elsewhere that mere 

 position in space is not. a conclusive criterion of the sequence of depo- 

 sition. Figure 4a shows cross-bedding of coarse sacchroidal quartzite 

 which has been truncated and covered over by a very coarse sand con- 

 taining angular fragments as much as three-fourths of an inch across. 

 It is very difficult to conceive of the reverse order. In that case the 



