Vol. 5] 



Weaver. — San Pablo Formation. 



259 



does not appear to be represented in the section at Kirker 's Pass, 

 or Markeley Canon. It is possible that the white chalky shales 

 at the base may be the equivalent of the Scutella zone, but there 

 is no direct evidence of any kind to support it. The total fauna 

 is much more varied in the number of species than at San Pablo 

 bay, but it approaches more closely in its affinities that of the 

 Astrodapsis tumidus zone, or the upper division. 



On the south side of Mt. Diablo, in the localities at Tassajero 

 Canon and Railroad Ranch, the San Pablo fauna, while not very 

 large, appears to bear its closest resemblance to that of the Astro- 

 dapsis zone, and to be the ecpiivalent of the San Pablo at Kirker 's 

 Pass and at Markeley Canon. The lower beds here contain large 

 numbers of the species Ostrea titan. Whether this is a charac- 

 teristic lower San Pablo fossil or not, is uncertain. It occurs in 

 the lower beds in the San Pablo Bay section ; it occurs only in the 

 lowermost beds at Tassajero Canon, and it is probable that the 

 two are nearly equivalent. The fossil leaves referred to by Mr. 

 H. W. Turner 113 came from the conglomerate tuff and sandstone 

 overlying the fossiliferous sandstone, and according to Lesque- 

 reux are considered as being of Pliocene age. They were deter- 

 mined as follows : 



Diospyros virginiana, var. turneri Lx. 

 Magnolia calif ornica Lx. 

 Laurus, cf. canariensis Heer. 

 Vvrburnum, cf. rugosus Pers. 

 Vit is, sp. ( f ) 



Those collected later, in 1897, by Professor Merriam and Mr. 



Turner are also considered Pliocene, but the general appearance 



of the bed would seem to indicate that they do not belong to the 



San Pablo, but rather to the Pinole Tuff. The list is as follows : 



Fern, probably Pteris, but very fragmentary. 



Populus, female catkin. 



AhvuS, fruits and leaves. 



Castanea, sp., leaf. 



Vaccinum, sp., single small leaf. 



Arbutus, sp., numerous well preserved leaves and fragments. 



In the upper beds at Tassajero Canon are strata composed of 

 vast numbers of specimens of Pseudoeardimn gabbi. This form 



i« Jour. Geol., vol. 6, pp. 483-499. 



