1922] 



Vaughan: Geology of San Bernardino Mountains 



359 



About a mile east of Doble a small mass of granite intrudes both 

 the Furnace limestone and the Saragossa quartzite. From this point 

 the contact between the two formations can be readily followed south- 

 westward to Round Valley, although somewhat complicated by fault- 

 ing, and in many places the limestone can be seen dipping beneath 

 the quartzite at angles of from 20° to 60°. Along the side of the old 

 road one mile and a half northwest of the Rose Mine is exposed a 

 section in which the quartzite, schist, and limestone are found repeated 

 in section. It exemplifies the degree to which faulting has affected 

 the region and how complex some of the detailed structure must be. 



On the ridge which forms the northwestern limit of Round Valley 

 the quartzite is separated from the limestone by a few feet of chlorite 



Tig. 5. Section through Gold Mountain showing thickness of Saragossa 

 quartzite. 



and biotite schist and the whole series dips 35° to the southwest. Just 

 south of this place the quartzite is intruded by a tongue of granite 

 which has forced its way through the limestone. East of Broom Flat 

 the quartzite again is found resting on limestone. From here south- 

 ward to Cienaga Seca and thence westward two miles beyond Sugar- 

 loaf the quartzite is intruded by granite. North of Sugarloaf it rests 

 on limestone, but here again the contact is often obscure and may be 

 somewhat complicated by faulting. 



Northeast of Baldwin Lake the quartzite extends over into Hol- 

 comb Valley, where it is intruded by granitic rocks. In many places 

 near the contacts the bedding of the quartzite is entirely obliterated 

 and inclusions of quartzite are found in the granite. Near Burnt 

 Flat it is in contact with the limestone, but it is not known whether 

 this contact is one of sedimentation or is a fault. 



On the south side of Baldwin Lake the quartzite has a granular 

 appearance for the most part and is hard and brittle like glass. It 

 varies considerably in color : white, yellowish white, light and dark 



