260 



University of California Publications. 



[Geology 



appears to be characteristic of the upper San Pablo. To the 

 south, just below Danville, fossiliferous beds occur, which yielded 

 a typical upper San Pablo fauna. They occur in a quarry just 

 west of the county road, where some of the outcropping' strata 

 are very largely composed of fossil marine shells. Altogether 

 eighteen species are present, and they are mostly characteristic 

 of the Astrodapsis zone. Among the more characteristic of these 

 are Astrodapsis tumidus, Cliione succincta, Pectcn veatcltii, Pec- 

 tunculus near patulus, and Pseudocardium gabbi. 



At "Walnut Creek the San Pablo is represented by both the 

 upper and lower beds. The lower or Scutella gabbi beds outcrop 

 in Walnut Creek, just out of the town. Fossils are abundant, 

 but rarely well preserved. To the westward at Lafayette San 

 Pablo fossils occur, and while they are few in number of species, 

 yet they indicate the lower portion, or perhaps the Scutella zone. 



On the north side of San Francisco bay the San Pablo occurs 

 at Carneros Creek, and to the northwest of Vacaville in Pleas- 

 ant's Valley. The fossils collected at Pleasant 's Valley were 

 very poorly preserved and fragmentary. Pseudocardium gabbi 

 was recognized. Provisionally this belt has been considered San 

 Pablo, but more on petrographical and stratigraphical evidence 

 than upon palaeontological. It lies unconformably upon the 

 Shasta-Chieo series, and is overlaid by the Orindan, the Pinole 

 Tuff, and lavas. The beds at Carneros Creek are certainly San 

 Pablo in age. While the fauna is not large, it is typically San 

 Pablo. The general physical appearance of the rock is also 

 characteristic of the San Pablo at the localities where it is best 

 developed. Just what portion of the formation it represents is 

 not clear, as the fauna is not large and not characteristic of any 

 one zone. The species occurring' here are given in the general 

 correlation table and are not listed separately. 



In the following table is given a complete list of all the known 

 San Pablo species from the localities studied in middle Califor- 

 nia, and their characteristic situation whether in the lower middle 

 or upper portions is also given. Such forms as range back into 

 the Monterey and those occurring in the Merced, Wildcat, Santa 

 Margarita, Etchegoin, Purisima, and those living in the waters 

 of the Pacific Coast of North America at the present time are also 

 indicated. 



