On,; 



GEOLOGIGAL SECTION OF MIDDLE COAST RANGES 545 



tions sufficiently close to afford a general idea of the section. Other features of 

 the paper are the subdivision of the Franciscan into seven stratigraphic subdi- 

 visions by the recognition of a persistent horizon of foraminiferal limestone and 

 two important horizons of radiolarian chert; a similar subdivision of the Mon- 

 terey into seven stages and a summary announcement of the character and history 

 of the post-Monterey Tertiary. The essential features of the paper are given in 

 the following tabulation : 



Geological Section of the Coast Ranges of California in the Vicinity of the Bay of San Francisco 



Thickness 

 Feet 



Merced \ Upper marine sandstones, sandy shales, and clay shales ) 5 „„„ 



( Lower marine clays, sandy shales, sandstones, fine pebbly conglomerates ) 



Unconformity. 



Campan 1 ' Volcanics, andesites, basalts, rhyol,ite agglomerates \ 500 



\ Fresh-water conglomerates, sandstones, clays, limestones f 



Unconformity. 



f Volcanics, basalts, and tuffs ^ 



, T „ , , Siestan, fresh-water clays, limestones, sandstones, shales, lignite, tuffs, 

 I . Berkeleyan^ ' J ' ' M- 200 

 conglomerates j 



L Volcanics, andesites, basalts, rhyolite tuffs J 



- Unconformity. 



j Volcanics, andesites, basalts, rhyolite tuffs \ 



L. Berkeleyan-j Trampan, marine shales, sandstones, pebbly conglomerates / ' 



I. Orindan, fresh-water conglomrates, sandstones, clays, limestones, tuffs... 2,400 



Pinole— Tuffs (pumiceous) fossiliferous 1,000 



San Pablo— Blue tuffaeeous sandstone, marine 1,500 



Unconformity. 



{ Upper Stage 7— Sandstone 1,800 



| Stage 6— Bituminous shale 670 



! Stage 5— Sandstone 1,200 



Monterey -j Middle \ Stage 4— Bituminous shale 460 



j Stage 3— Sandstone 600 



[Stage 2— Bituminous shale and chert 250 



[Lower Stage 1— Sandstone 400 



Unconformity. 



J Tejon — Massive sandstones 2,100 



\ Martinez — Massive sandstones 2,200 



Rhyolite flows. (Age not certainly determined*.) 

 Unconformity. 



f Chico— Sandstones and shales 3,000 + 



, . I Oakland— Conglomerate 500 



Shasta-Chico j Peridotite irruptions. 



[Knoxville— Shales with subordinate limestone and conglomerate 1,000 



Unconformity. Volcanics. 



\ Bonita sandstone 1,400 



I San Miguel cherts, radiolarian 530 



i Marine sandstone 1,000 



I Sausalito cherts, radiolarian 900 



Franciscan -J Bolinas sandstone (volcanics) 2,000 



Volcanics. 



Calera limestone, foraminiferal 60 



Volcanics. 

 i Pilarcitos sandstone 790 



34,290 

 Unconformity. 

 Montara granite (correlated tentatively with late Jurassic granite of Sierra Nevada). 



The Section then adjourned for luncheon. 



