VOLUME XIX 



NUMBER 5 



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 



GROVE K. GILBERT, National Survey, Washington, D.C. 

 CHARLES D. WALCOTT, Smithsonian Institution 

 HENRY S. WILLIAMS, Cornell University 

 JOSEPH P.IDDINGS, Washington, D.C. 

 JOHN C. BRANNER, Stanford 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 



JULY- AUGUST, 191 1 



CONTENTS 



SAMUEL CALVIN -------------------- H. Foster Bain 385 



THE EVOLUTION OF LIMESTONE AND DOLOMITE. II - - Edward Steidtmann 392 



DIFFERENTIATION OF KEWEENAWAN DIABASES IN THE VICINITY OF LAKE 



NIPIGON ---------------------- E. S. Moore 429 



GENERA OF MISSISSIPPIAN LOOP-BEARING BRACHIOPODA - - Stuart Weller 439 



PHYSIOGRAPHIC STUDIES IN THE SAN JUAN DISTRICT OF COLORADO 



Wallace W. Atwood 449 



THE VARIATIONS OF GLACIERS. XVI -------- Harry Fielding Redd 454 



PETROLOGICAL ABSTRACTS AND REVIEWS --------- 4 6 2 



REVIEWS ---------------------------._ 469 



C^e anftiergiti? of Chicago p?z$$ 



CHICAGO, ILLINOIS 



Agents : 



THE CAMBRIDGE UNIVERSITY PRESS, London and Edinburgh 



WILLIAM WESLEY & SON, London 



TH. STAUFFER, Leipzig 



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



