COMPARISON OF FOUR SANDSTONES. 411 



aud the phthaiiite can be readily separated from the shale. lu most cases 

 the color is brownish red, as in the samples analyzed ; but often greens and 

 grays are represented, the latter especially when white granular quartz in- 

 termingles with these. Throughout this phthanite, quartz seams a few mil- 

 limeters wide intersect each other in a kind of network, and sometimes 

 crystals of quartz are noticed. Likewise the red shale exhibits the same 

 amount of quartz. In the analyses the shale was freed from quartz, an easy 

 matter, aud also the purest fragments of phthanite were selected for analysis. 



Series V — Analyses of Shales from the Head of Bagley Creek, 



Loss at 100° C 



Loss above 100° C. 

 Si02 



PA 



AlA 



FeA ____ 



FeO 



MnO 



CaO 



MgO 



K,0 



Na20 



Series VI. — This series consists of four sandstones, two of which are from 

 the metamorphic area. 



a. Upper Cretaceous, Chico sandstone ; light brown, fine granular, rather 

 soft ; clastic grains of mica and feldspar observed. 



h. Lower Cretaceous, Neocomian sandstone ; from the head-waters of Bag- 

 ley creek ; hard, granular, greenish. 



c. Miocene sandstone from near Wall point ; granular, small light-brown 

 and black particles evenly distributed ; very friable. 



d. Chico sandstone with fossil, Trigonia evansana; compact crystalline ; 

 color greenish-gray. 



Analyses of these sandstones were made in order to give an account com- 

 plete as possible of the varieties of rocks in the region which was studied, 

 quite as well as for the sake of comparing their composition. They have 

 no bearing upon the points which are discussed in the previous pages. 



(186) 

 a 



(185) 

 b 



1.03 



0.21 



2.92 



0.72 



69.98 



93.54 



0.05 







11.69 



2.26 



6.23 



0.48 



1.08 



0.79 



0.49 



0.23 



0.38 



0.09 



1.29 



0.66 



3.72 



0.51 



0.73 



0.37 



99.59 



99.86 



