COAST LINE LOS ANGELES TO SAN FRANCISCO. 



101 



The light-colored beds showing low iu the hills behind the derricks 

 belong to the Sespe formation (Oligocenc). Above them are darker 

 beds belonging to the Vaqueros sandstone Gower Miocene). The 

 very lightest bods at the top are the Monterey shale 



running northward from the Simi Valley 



shale (Miocene), 

 in some of the canyons 



the 



hiUs immediately south of the town of Santa Susana consist 

 ity beds of the Sespe (Oliizocene) formation. Farther back i 



the underlying Topatopa (Eocene) beds. Still farther south the 



Monica Ranse consists of a thick series of Ci'et 



rocks 



complicated masses of isrneous rocks 



of 



Miocene 



•imi Valley 



general form to the folding and faulting of the 



chiefly 



— that is, it is 



erosion. 



filled with alluvium to an unknown 



On the 



line 



■defined sag in the strata (a syncline) 



most 



This northern ranj^e 



forms the south side of Santa Clara Valley* from Saugus to Ventura. 

 On both sides of that vaUey are productive oil fields that yield petro- 

 leum ranging from a heavy, tarry oil to an oil of very light gravity 

 that is much soucrht after bv the refiners of illuminatiner oil.^ 



There 



vraa 1,042,348 barrels, most of which waa 



Calif or iiia — on e 



Los Angelea counties, drained by Santa 



■known 



lowland juat south of San Francisco Bay, 

 in Santa Clara County. The traveler 

 from Lo9 Angeles to San Francisco passes 

 through parts of both of these valleys and 



mind 



TheSf 

 produc 



obtained 



ago from tunnels driven near Ventura and 

 on the south flank of Sulphur Mountain. 

 The firat productive well in California was 

 drilled near Ventura in 1867. Tlae dis- 

 trict includes the r^ion on both sides of 

 Santa Clara River from the NeM^hall field, 

 m Loa Angeles Coimty, 40 miles northwest 

 of Loa Angeles, to the Ojai Valley field, in 

 Ventura County, about 50 miles farther 

 west. The Santa Clara district produced 

 practically all the oil in the State up to 

 1880, when the Puente Hills district was 

 discovered. The bulk of the production 

 la of refining grade. Tlie yield in 1913 





piped to seaboard. 



Tlie district comprises 13 fields, some of 

 which are in almost inaccessible places, 

 the productive territory being confined to 

 very narrow strips along the crests of sharp 

 folds. The wells range in depth from 200 

 to 3,700 feet J a large number being less 

 than IjOOO feet deep. It is estimated that 

 the average depth of the wells is less than 

 in any other district in the State, 



Tlie hea\aest oil, ranging from 11° to 10° 

 Baimi6, is found in the Ojai Valley, Hop- 

 per Canyon, and Elsmere Canyon fields. 

 Practically all the other fields yield refin- 

 ing oil ranging from 23° to 38° Baum^. 

 The wells vary greatly in capacity, some 

 having an initial flow of 500 to 600 barrels 

 a day and some being profitably operated 

 for a yield of 2 barrels a day or even less. 

 It is estimated that the average daily pro- 

 duction per well for the entire district in 

 1913 was 7.2 barrels. 



Although practically all the fields have 

 been operated for many years, the terri- 

 tory is by no means all prospected, and 



