wright-fenner] 



PETEOGRAPHIC STUDY 



79 



-All of these specimens contain some sodium chloride. They are 

 indurated and do not break down and disintegrate as does the loess 

 when immersed in water. 



23. 34 



60. 95 



1.63 



85.92 



9.44 



100.23 



Ratios 



.,1 Sal 85.92 7 



Class =^ — = „ , , > V I 



Fem 9.44 1 



n 1 Q 23.34^3^1 



^''^^' ? = 60T95<5>7 ^ 



^ K,0'+Na20' .080 5 3 



^^^g " CaO- == :065<3>5 \ 



Q 1 K^O- .024^3^1 



^"^^™- NCT^= :056<5>7 ^ 



I. Scoria, Miramar. J. G. Fairchild, United States Geological 



Survey, analyst, 

 la. Molecular proportions of I. 



Except for the high percentage of water this analysis might easUy 

 be mistaken for that of a biotite-granite or granodiorite or quartz- 

 mica-diorite. It differs from the analysis of the scoria from Alvear 

 in its noticeably higher alkali content and consequent less amount 

 of corundum and quartz in the norm. Both the lime and magnesia 

 are higher, but their proportions do not suggest any abnormality in 

 the composition, if the rock were considered an eruptive rock. The 

 eruptive material predominates to so great an extent that it determines 

 the general character of the analysis. 



