SHASTA ROUTE SEATTLE TO SAX FRANCISCO, 



81 



railroad 



Just 



(Mi 



slioAvn in a 'h\g 



Martinez 



Works ^ where the buff-colored Montercj 



m 



shales. 



wi 



boring Miocene mollusks. The Monterey beds are 



cliff: 



vn 



iT 



thill 



After leavin 



crosses a little swamp, and approaches a tumiel cut into vertical 

 cliffs of massive gray sandstone; this is the type locality of the San 

 Pablo formation (upper Mocene), The refining plant of the Union 

 Oil Co., at the east end of this tunnel, is located on the upper part 

 of the San Pablo beds. Vertical beds of massive tuff immedi?itely 

 west of the oil refinery represent the lower part of the Pinole tuff. 

 Beyond these beds the tram crosses another swamp and enters a 

 cut in which white volcanic ash beds of the Pinole tuff dip at a 

 relatively low angle to the northeast. This change in dip shows 

 that these beds are on the southwest side of the San Pablo Bay 

 syncline, the axis of which passes through the swamp area. Eestmg 

 upon the tilted ash deposits in this part of the section are horizontal 

 beds of Pleistocene shale, 



The name Rodeo (ro-day'o), meanmg '^round-up/' mdicates that 

 the station so called was formerly a cattle-shipping point. Beyond 



Rodeo. 



Elevation 12 feet, 

 Seattle 932 milfts. 



Rodeo the train enters a series of cuts. Near the sta- 

 tion are exposures of massive tuffs close to the base of 

 the Pmole tuff. Beyond this point the San Pablo 

 (Miocene) appears, with low dips to the northeast. 



om 



are excellent exposures of the Miocene capped by Pleistocene shale. 



Hercules, where there are laro-e nowder works 



8,000 feet. With the exception of the I in the same formation a few miles to the 

 Pliocene and a portion of the Pleistocene, ] east. The 

 all the formations are of marine origin. 



A portion of the Pinole tnff was certainly 

 deposited in fresh water. The Pleisto- 

 cene beds were deposited under varying 

 marine, eatuarine, and fluvial conditions. 

 Fossil remains are found in all the for- 

 mations of the San Pablo Bay section, 

 and at least six distinct faunaa are repre- 

 sented. Very few specimens have been 

 procured in the Chico near the line of the 

 railroad, but abundant fossila are found 



in the cliff opposite the Selby smelter. 

 Tlie Monterey and the San Pablo con- 

 tain abundant remains. The fresh-water 

 fauna of the Pinole tuff is represented by 

 molluscan species- Leaves and remains 

 of vertebrates are also present. Th e 

 Pleistocene shale contains abundant 

 marine shells of a few species, with mam- 

 mal bones representing the elephant, 



:am 



forms 



9628G°— Bull. B14— 1& 



« 



