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July-August 1922 Vol. XXX, Na. s 



The Journal of Geolog 



Edited By 

 thomas c. chamberlin and rollin d. salisbury 



With the Active Collaboration of 

 STUART WELLER ALBERT JOHANNSEN 



Invertebrate Paleontology Petrology 



EDSON S. BASTIN ROLLIN T. CHAMBERLIN 



Economic Geology Dynamic Geology 



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