56 University of California Publications in Geology ["Vol. 7 



together with tree trunks standing at right angles to the dip ; 

 (3) by the character of the deposits found along this zone; i.e., 

 a very tuffaceous, angular-grained, cross-bedded sandstone. 



In the section just referred to, immediately above the hard 

 layers of sandstone, there is a layer of medium-coarse, tuffaceous, 

 angular-grained, concretionary sandstone between ten and fif- 

 teen feet thick. This layer is very much cross-bedded, and, like 

 the cross-bedded sandstones below the hard layers, suggests 

 that they are sand-dune deposits. The tuffs in these sandstones 

 and the conglomerates above the basal beds of the Lower Division 

 were determined by Turner as andesitic in origin. 7 



The Upper Division of the San Pablo series has a thickness 

 of about 250 feet ,and consist mainly of coarse to medium-fine, 

 bright-blue vivianitic sandstones, alternating with irregular 

 bands of light-buff clays. At a number of horizons these clays 

 have a thickness of several feet, and are thin-bedded and may be 

 classed as a shale. The sandstones are the predominating phase 

 of this division. 



One of the noticeable features of this part of the series 

 is that the contacts between some of the clay layers and the 

 sandstones are slightly irregular, and the change from a sand- 

 stone to a clay is often very sharp. Another thing that is to 

 be noted is that leaf impressions and silieified wood are very 

 common at different horizons in both the sandstones and the 

 clays. It was in the upper part of this division that Turner's 

 leaf collection of 1897 was obtained. 8 



The following flora obtained by Turner from this horizon was 

 determined by Professor F. H. Knowlton : 



Fern, probably Pteris, but very Castanea, sp. leaf. 



fragmentary. Vaccinum, sp. single small leaf. 



Populus, female catkin. Arbutus, numerous well-preserved 

 Alnus, fruits and leaves. leaves. 



Fauna of Upper Division. — Good fossil localities in the Upper 

 Division of the San Pablo are very rare. Shells are found at 

 several horizons, but in nearly all cases they are very poorly 



" Jour. Geol., vol. 6, p. 497, 1898. 

 s Idem., vol. 6, p. 498. 



