Vol. 6] Jones: The Geology of the Sargent Oil Field. 



71 



the range of hills formed by the resistant plutonic rock. The 

 fossils throughout the formation are not generally scattered but 

 are localized in beds from a few inches up to several feet in 

 thickness. These beds are very hard and have prevented 

 excessive erosion of the formation as a whole. 



The recent Santa Cruz folio by Braimer, R. Arnold, and 

 Newsome notes Purisima beds along the east flank of the Santa 

 Cruz range and limits the Merced to the sea-coast. It is evident 

 that during Merced time a deep bay or strait existed over the 

 Pajaro Valley region and that Merced sediments were deposited 

 in this trough as far inland as the Santa Clara Valley. 



The following fossils were identified from the formation 

 here called Merced : 



Area trilineata 

 Area microdonta 

 Standella calif ornica 

 Standella falcata 

 Tresus nuttalli 

 Macoma nasuta 

 Callista subdiaphana 

 Solen sicarius 

 Mytilus, sp (?) 

 Mi/tilus edulis 

 Ostrea, sp (?) 



P u rp u ra ea n a lie u lata 

 Purpura, sp ( ?) 

 Crepidula princeps 

 Neverita reclusiana 

 Olivella boetiea 

 A mycla gausapata 

 Amycla undata 

 Nassa perpinguis 

 Echinarachnius excentrieus 

 Balanus, sp ( ?) 



FRESH- WATER FORMATION. 

 Exposed all along the Southern Pacific Railroad track for 

 a mile south of Sargent is a thick formation of clays, sandstones, 

 and gravels which are undoubtedly, in the main, of fresh-water 

 origin. These beds flank the eastern slope of the Santa Cruz 

 range and in general dip towards the Santa Clara Valley, 

 though in places they are quite highly tilted and their structure 

 is slightly complicated. The total thickness of the formation 

 is at least 800 feet. Near the junction of the San Benito and 

 the Pajaro valleys the discordance in dip and strike between the 

 beds which have been called Merced and these fresh-water beds 

 points towards at least a local unconformity between the two, 

 but this is not certain. The fresh-water formation rests on San 

 Pablo, Monterey, and Franciscan rocks farther north. The 

 formation yields no outcrops except in intrenched creek beds 



