1922] Vaughan: Geology of San Bernardino Mountains 



375 



sandstone is not exposed and the top has been eroded away, this repre- 

 sents a minimum estimate of its original thickness. 



The age of this sandstone has not been definitely determined. The 

 intense shearing and induration indicate that it is older than the 

 Hathaway formation or the Santa Ana sandstone. Its position rela- 

 tive to the Saragossa is obscure, but its freedom from intrusive rocks 

 and the fact that much of it is unaltered, except that it is well indu- 

 rated, suggest that it is younger. Lithologically it resembles many 

 of the Tertiary sandstones of the Coast Ranges ; for example, the 

 Puente Sandstone of Miocene Age in the Santa Monica Mountains. 

 As other considerations are not adverse to this, the formation will 

 tentatively be considered as Miocene. 



The Lion sandstone. — About half a mile from the mouth of Lion 

 Canon there is a branch to the northwest which, near its upper end, 

 cuts across the Hathaway formation, a series of land-laid deposits; 

 shaley playa beds, coarse sandstone, and fanglomerate, all dipping 

 from 20° to 70° to the north. Overlying them in angular discordance 

 is a flow of basalt. This also dips to the north, but not quite so steeply. 

 On the third ridge west of Lion Canon there is a small outcrop of 

 sandstone, about a quarter of a mile long, dipping 45° north. Its 

 exact relationship to the land-laid series is not clear. The southern 

 limit of the latter, east and west of this point, is a fault, but the rocks 

 are so similar and their detritus so intermingled that the contact on 

 this ridge is obscure. If the fault is in line with the better exposures 

 on each side, then it passes south of the small sandstone outcrop. This 

 would mean that the sandstone has been faulted with the Hathaway 

 formation and, since it dips toward the latter, it probably passes 

 beneath and therefore underlies it. If the fault passes north of the 

 sandstone, however, the latter is separated from the Hathaway but 

 may be thrust from below. In either case the sandstone is the older. 

 It is not likely that the sandstone has been dropped from above, for 

 in that case we should expect to find it elsewhere. 



This sandstone contains a small marine fauna consisting of forms 

 found by Kew 21 in the Carrizo Creek region. The most important of 

 these are : a Turritclla compared to altalira, a Spondylus, Pecten sub- 

 nodoses, and some other pectens not yet described. Of the Carrizo 

 Creek fauna Kew says: "The echinoderm fauna seems to indicate a 

 comparatively late age, as several of the forms are very closely related 

 to the species living in the Gulf of California at the present time, and 



21 Kew, W. S. W., Tertiary echinoids of the Carrizo Creek region in the 

 Colorado Desert, Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, no. 5, pp. 39-60. 



