CLASSIFICATION OF THE PLUTONIC ROCKS 261 



in the same (in this case, the Intermediate) group. The figures 

 show the comparatively high lime, magnesia, and iron in the 

 representative of the Calc-alkali Series, the greater proportion of 



I. Diorite. 



Fig. 8. 

 II. Monzonite. 



III. Soda-syenite. 



alkalies without diminution in lime in the Monzonite, and the 

 greatly increased alkalies with diminished lime, magnesia, and 

 iron in the representative of the Alkali Series. 



If a further justification for the division of the igneous rocks 

 into series be required, there is the fact that although the 



