VOLUME XXIII SUPPLEMENT TO NUMBER 8 



THE 



JOURNAL OF GEOLOGY 



NOVEMBER-DECEMBER igis 

 SUPPLEMENT 



THE LATER STAGES OF THE EVOLUTION OF THE 

 IGNEOUS ROCKS 



N. L. BOWEN 

 Geophysical Laboratory, Carnegie Institution of Washington 



CONTENTS 



Introduction 

 Differentiation 

 The Soret Action 



Gravitative Effect in a Liquid Magma 

 Separation of Distinct Phases 



Liquid Immiscibility in Magmas 

 Differentiation through Crystallization 

 The Association of Diabase and Micropegmatite 

 The System Diopside-Forsterite-Silica 



Crystallization with Perfect Equilibrium 

 Crystallization with Zoning 



Crystallization When the Crystals Are Free to Sink in the Liquid 

 Crystallization with Straining Off of the Liquid 

 The System Anorthite-Forsterite-Silica 

 Crystallization in Systems Involving the Plagioclases 

 Crystallization of the Plagioclases in the Binary System 

 Crystallization in the System Diopside-Anorthite-Albite 

 Crystallization with Perfect Equilibrium 

 Crystallization with Great Undercooling 

 Crystallization with Zoning 

 Crystallization with Subsidence of Crystals 

 The Effect of Rate of Cooling Summarized 

 Conclusions to Be Drawn from the Investigated Ternary Systems 

 The Importance of the Formation of Biotite 

 Equilibrium in Silicate Liquids 



Equilibria in Magmas Indicated by Minerals Precipitated 

 The Crystallization of Basaltic Magma 

 Field Evidences of the Control of Crystallization in Differentiation 



