310 University of California Publications in Geology [Vol. 11 



free from calcium carbonate and are very finely laminated, the lam- 

 inae being about one millimeter thick. They occur in thin beds rang- 

 ing from 2.5 centimeters to 15 centimeters in thickness, occassionally 

 reaching a thickness of 30 centimeters. 



The radiolarian claystones contain abundant plant remains. 

 There are numerous impressions of Lepidodendron australe, some of 

 which still contain carbon. In places these remains are very abun- 

 dant, three to ten leaf impressions occurring per square foot of 

 surface. 



The radiolarian claystones show evidence of shallow water deposi- 

 tion. In two places near Tamworth, ripple marks were found in them. 



Lenticular beds of a siliceous limestone occur at various horizons, 

 irregularly interstratified with the other rocks. The thickness of these 

 lenses ranges from a few inches to two feet. They contain numerous 

 radiolaria. 



Dense, black radiolarian cherts occur locally. In thin section, 

 they are seen to be laminated, the lamination being due to alternate 

 bands of lighter and darker material. The radiolaria appear as clear 

 areas in a darker matrix consisting of silica containing particles of 

 carbonaceous material. The radiolaria are generally filled with chal- 

 cedonic silica, but occasionally they are filled with granular quartz. 

 They are very numerous, it being estimated that each cubic inch of 

 the rock contains about 1,000,000 radiolarian skeletons. 



The following analyses by David and Palmer indicate the chem- 

 ical nature of various rocks of this series : 



I. 



Black radiolarian chert. 







II. 



Radiolarian 



cherty shale. 







III. 



Radiolarian 



shale. 



I 



11 



III 





Si0 2 





91.06 



80.50 



67.87 





A1 : 3 





3.79 



9.57 



15.25 





Fe 2 3 





2.01 



2.67 



5.08 





MnO 





trace 



trace 



trace 





CaO 





.45 



.60 



1.71 





MgO 





.46 



.76 



1.46 





K 2 





.84 



1.68 



2.21 





Na 2 





.28 



1.18 



1.37 





C0 2 









absent 





P 2 5 





trace 



.11 



.12 





so 3 





.35 



trace 







Organic matter 





.86 







Water 



@ 100°C 



.32 



.45 



2.37 





Combined water 



.97 



1.29 



2.10 









100.53 



99.67 



99.54 



