96 PROCEEDINGS OF THE CORDILLERA X SECTION 



GENERAL GEOLOGY OF THE SAN JOSti AND MOUNT HAMILTON QUADRANGLES 



BY E. C. TEMPLETON 



(Abstract) 



The oldest exposed rocks on the San Jose and Mount Hamilton quadrangles 

 belong to the Franciscan series and consist of sandstones and shales, with an 

 occasional bed of heavy conglomerate; of jaspers and of the typical metamor- 

 phics (glaucophane schist and gneiss and greenstone), which occur in small, 

 widely distributed areas. A large proportion of the sandstones and shales are 

 schistose in appearance, although considerable areas of unaltered portions of 

 these beds exist. The total thickness of the Franciscan series represented is 

 between 15,000 and 20,000 feet. This series occurs principally east of the 

 Calaveras-Sunol fault. 



The Knoxville beds overlie the Franciscan unconformably. They consist of 

 shale, conglomerate, and sandstone, carrying Aucella piochi and Aucella crassi- 

 collis. Their total thickness is about 10,000 feet. 



The lowest Miocene sandstone belongs to the Temblor phase of the Monterey 

 series and rests unconformably on the Franciscan, the Knoxville beds being 

 here lacking. It has an abundant fauna, typically Temblor. Its thickness is 

 about 1,000 feet. Overlying it is the Monterey shale, hard, light-colored, and 

 siliceous, with a thickness of about 1,200 feet. West of the Calaveras-Sunol 

 fault this shale rests unconformably on the Knoxville, with the Lower Mio- 

 cene sandstone beds lacking. 



The Monterey shale is overlaid, apparently conformably, by a thickness of 

 about 3,500 feet of sandstone, with a typical Temblor fauna. Above this, with 

 a slight unconformity separating them, is a red conglomerate, with a thickness 

 of 1,800 feet It is doubtfully Santa Margarita. 



A great unconformity separates the earlier beds from the fresh-water Santa 

 Clara beds, which have a wide distribution west of the Calaveras-Sunol fault. 



The mountains of the San Jose and Mount Hamilton quadrangles are highly 

 folded and considerably faulted. The Calveras-Sunol fault, which cuts through 

 Calaveras, Halls, and San Felipe valleys, divides the region into two areas, 

 which are geologically almost distinct. The ridges on the two sheets are prin- 

 cipally synclinal, and the valleys anticlinal or fault valleys, with the excep- 

 tion of the Santa Clara, which appears to be a great syncline. 



Presented without notes; illustrated by maps, geological sections, and 

 geological columns. Discussion by Clark, Louderback, and Lawson. 



IRON-ORE DEPOSIT AT BARTH, NEVADA 

 BY J. CLAUDE JONES 



(Abstract) 



The Barth deposit of iron ore is a large, irregular mass of hematite inclosed 

 in a basic andesite. The hanging wall contact is usually sharply denned, al- 

 though some slipping has taken place between the ore and the andesite. In 

 places the contact is quite irregular and the hanging wall pitted as if cor- 



