

April-May 1923 , Vol. XXXI, N<^. 



The Journal of Geolog 



Edited By 

 thomas c. chamberlin 



With the Active Collaboration of 



ROLLIN T. CHAMBERLIN, Managing Editor 

 Dynamic Geology 

 STUART WELLER ALBERT JOHAl^NSEN 



Invertebrate Paleontology Petrology 



EDSON S. BASTIN J HARLEN BRETZ 



Economic Geology Stratigrapbic Geology 



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