VOLUME XXVIIl 



NUMBER 6 



THE 



Journal of Geology 



A Semi-Quarterly J^'"^' 



\i^ APR Z S 



Edited By 

 thomas c. chamberltn and rollin d. salisbl 



With the Active Collaboration of 



fevAwMOSS 



STUART WELLER, Invertebrate Paleontology ALBERT JOHANNSEN, Petrology 



ROLLIN T. CHAMBERLIN, Dynamic Geology 



ASSOCIATE EDITORS 



SIR ARCHIBALD GEIKIE, Great Britain 



CHARLES BARROIS, France 



ALBRECHT PENCK, Germany 



HANS REUSCH, Norway 



GERARD DeGEER, Sweden 



T. W. EDGEWORTH DAVID, Australia 



BAILEY WILLIS, Leland Stanford Junior University 



CHARLES D. WALCOTT, Smithsonian Institution 



JOSEPH P. IDDINGS, Washington, D.C. 



JOHN C. BRANNER, Leland Stanford Junior University 

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

 WILLIAM H. HOBBS. University of Michigan 

 FRANK D. ADAMS, McGill University 

 CHARLES K. LEITH, University of Wisconsin 

 WALLACE W. ATWOOD, Harvard University 

 WILLIAM H. EMMONS, University of Minnesota 

 ARTHUR L. DAY, Carnegie Institution 



SEPTEMBER-OCTOBER 1920 



DIASTROPHISM AND THE FORMATIVE PROCESSES. XII. THE Pm^SICAL PHASES 

 OF THE PLANETARY NUCLEI tiURING THEIR FORMATIVE STAGES 



T. C. Chamberlix 473 



NOTES ON THE MECHANICS OF GEOLOGIC STRUCTURES - - W.arren J. Mead 505 



PRELIMINARY DESCRIPTION OF A NEW SUBORDER OF PHYTOSAURIAN REPTILES 



WITH A DESCRIPTION OF A NEW SPECIES OF PHYTOSAURUS - E. C. Case 524 



THE HEART MOUNTAIN OVERTHRUST, WYOMING 



- D. F. Hewett 536 



SUMMARIES OF PRE-CAMBRIAN LITERATURE OF NORTH AMERICA 



Edward Steii>tmanx 558 



THE UNIVERSITY OF CHICAGO PRESS 



CHICAGO, ILLINOLS, U.S.A. 



THE CAMBRIDGE UNIVERSITY PRESS, London 



THE MARUZEN-KABUSHIKI-KAISHA. Tokyo, Osaka, Kyoto, Fukuoka, Skndai 



THE MISSION BOOK COMPANY, Shanghai 



