VOLUME XXil 



NUMBER 7 



THE 



Journal of Geology 



A Semi-Quarterly 



Edited By 

 thomas c. chamberlin and rollin d. salisbury 



With the Active Collaboration of 



SAMUEL W. WILLISTON 



Vertebrate Paleontology 



STUART WELLER 



Invertebrate Paleontology 



ALBERT JOHANNSEN 

 Petrology 



WALLACE W. ATWOOD 

 Physiography 



WILLIAM H. EMMONS 



Economic Geology 



ROLLIN T. CHAMBERLIN 

 Dynamic Geology 



ASSOCIATE EDITORS 



SIR ARCHIBALD GEIKIE, Great Britain 

 *HEINRICH ROSENBUSCH, Germany 

 *THEODOR N. TSCHERNYSCHEW, Russia 



CHARLES BARROIS, France 



ALBRECHT PENCK, Germany 



HANS REUSCH, Norway 



GERARD DeGEER, Sweden 



ORVILLE A. DERBY, Brazil 



T. W. EDGEWORTH DAVID, Australia 



BAILEY WILLIS, Argentine Republic 



♦Deceased, 



GROVE K. GILBERT, Washington, D.C. 

 CHARLES D. WALCOTT, Smithsonian Institution 

 HENRY S. WILLIAMS, Cornell University 

 JOSEPH P, IDDINGS, Washington, D.C. 

 JOHN C. BRANNER, Leland Stanford Junior University 

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

 WILLIAM B. CLARK, Johns Hopkins University 

 WILLIAM H. HOBBS, University of Michigan 

 FRANK D. ADAMS, McGill University 

 CHARLES K. LEITH, University of Wisconsin 



OCTOBER-N IVEMBER 1914 



A SUMMARY OF THE OROGENIC EPOCHS IN THE GEOLOGIC HISTORY OF NORTH 



AMERICA ----_---.- Eliot Blackwelder 633 



THE STRENGTH OF THE EARTH'S CRUST. VI. RELATIONS OF ISOSTATIC MOVE- 

 MENTS TO A SPHERE OF WEAKNESS— THE ASTHENOSPHERE 



Joseph Barbell 655 



,A COMPARISON OF THE C(EUR D'ALENE MONZONITE WITH OTHER PLUTONIC 



ROCKS OF IDAHO ---------- -C.A.Stewart 684 



A GRAPHIC METHOD OF REPRESENTING THE CHEMICAL RELATIONS OF A PETRO- 



GRAPHIC PROVINCE - - . Frank D. Adams 689 



THE MODE OF FORMATION OF CERTAIN GNEISSES IN THE HIGHLANDS OF NEW 



JERSEY {Concluded) --------- Clarence N, Fenner 694 



A COMPARISON OF THE CAMBRIAN AND ORDOVICIAN RIPPLE-MARKS FOUND AT 



OTTAWA, CANADA ---------- E. M. Kinble 703 



NEW AND LITTLE-KNOWN INSECTS'* FROM THE MIOCENE OF FLORISSANT, 



COLORADO - - - - - T. D. A. Cockerell 714 



PETROLOGICAL ABSTRACTS AND REVIEWS - - - - 725 



THE UNIVERSITY OF CHICAGO PRESS 



CHICAGO, ILLINOIS, U.S.A. 



Agents 



THE CAMBRIDGE UNIVERSITY PRESS, London and Edinburgh 



KARL W. HIERSEMANN, Leipzig 



THE MARUZEN-KABUSHIKI-KAISHA, Tokyo, Osaka, Kyoto 



