May-June 1923 ' Vol. XXXI, No. 4 



The Journal of Geoloq 



\ 



Edited By 

 thomas c. chamberlin 



With the Active Collaboration of 



ROLLIN T. CHAMBERLIN, Managing Editor 

 Dynamic Geology 

 STUART WELLER ALBERT JOHANNSEN 



Invertebrate Paleontology Petrology 



EDSON S. BASTIN . J. HARLEN BRETZ 



Economic Geology Stratigraphic Geology 



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