April-May 1922 Vol. XXX, No. 3 



The Journal of Geology 



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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