1922] Vaughan: Geology of San Bernardino Mountains 395 



are the result of some sort of jointage system that existed before the 

 intrusion of the younger granite. 



South of Antelope Creek and Santa Ana Canon the older sediments 

 are so broken and contorted by folding, faulting, and granitic intru- 

 sions that a general statement of the structure is scarcely possible, and 

 what has been said under the description of these rocks must suffice. 

 This statement also applies to the rocks in the desert to the north. 



At its eastern limit the Potato sandstone dips nearly vertically or 

 very steeply to the west, but farther west it flattens considerably and 

 at the mouth of Mill Creek Canon, about two miles off the map accom- 

 panying this paper, it is nearly horizontal. 



The unaltered sediments along the south side of the range have 

 been somewhat warped and faulted. Between Deep Canon and Stubby 

 Canon the Hathaway formation dips from 20° to 70° to the north. 

 On a ridge about half a mile east of Deep Canon the Lion sandstone 

 appears to lie at the base of the Hathaway with a dip of 45° north, 

 but there has been so much faulting that this is not clear. 



Between Millard and Deep canons basalt overlies the eroded edges 

 of the Hathaway sandstone. It seems to form an anticline, the south 

 limb disappearing before reaching Deep Cailon, possibly due to fault- 

 ing. The north limb continues half a mile east of Deep Cailon and is 

 overlain by the Deep Canon fanglomerate which has been tilted with it. 

 Along the south side of the Hathaway formation between Deep and 

 Stubby canons there is a large mass of Cabezon fanglomerate, but 

 owing to its unconsolidated nature the contact is usually obscure. On 

 the ridge west of Lion Canon it is clearly a fault (fig. 7), but at the 

 south of Deep Canon it is depositional, the fanglomerate overlying the 

 sandstone and shale. 



The unconformity between the Hathaway formation and the basalt 

 can be seen at the mouth of Hathaway Canon on the west side, where 

 the former is tilted to dips as high as 45° and is overlain by the latter 

 with a dip of about 30° to the west. This in turn is overlain by nearly 

 horizontal Cabezon fanglomerate. 



Near the mouth of the canon west of San Gorgonio River the 

 Hathaway formation has a dip of 15° to the north, but farther up it 

 gets steeper and about 200 yards from the mouth of the canon the 

 dip is 45°. Near the head of the canon the sandstone projects through 

 the flat-lying fanglomerate with a strike of S 60° W and a dip of 45° 

 NW (fig. 6). In the canon two miles west of San Gorgonio River the 

 sandstone is faulted against the schist on the north and west and is 

 overlain by nearly horizontal fanglomerate on the east. 



