NH 



THE 



JOURNAL OF GEOLOGY 



A Semi-Quarterly Magazine of Geology and 

 Related Sciences 



EDITED BY 



THOMAS C. CHAMBERLIN 



With the Active Collaboration of 

 ROLLIN T. CHAMBERLIN, Managing Editor 

 STUART WELLER, Invertebrate Paleontology ALBERT JOHANNSEN, Petrology 



EDSON S. BASTIN, Economic Geology J HARLEN BRETZ, Stratigraphic Geology 



ASSOCIATE 



SIR ARCHIBALD GEIKIE, Great Britain 



CHARLES BARROIS, France 



ALBRECHT PENCK, Germany 

 *HANS REUSCH, Norway 



GERARD DeGEER, Sweden 



SIR T. W. EDGEWORTH DAVID, Australia 



H. ALBERT BROUEVER, Holland 



BAILEY WILLIS, Leland Stanford Junior Uni- 

 versity 



CHARLES D. WALCOTT, Smithsonian Institu- 

 tion 



*Deceased. 



EDITORS 

 DAVID WHITE, U.S. Geological Survey 

 RICHARD A. F. PENROSE, Jr., Philadelphia, 



Pa. 

 WILLIAM H. HOBBS, University of Michigan 

 FRANK D. ADAMS, McGill University 

 CHARLES K. LEITH, University of Wiscon- 

 sin 

 WALLACE W. ATWOOD, Clark University 

 WILLIAM H. EMMONS, University of Minne- 

 sota 

 ARTHUR L. DAY, Carnegie Institution 



VOLUME XXXI 



JANUARY-DECEMBER, 1923 



THE UNIVERSITY OF CHICAGO PRESS 

 CHICAGO, ILLINOIS 



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