VOLUME XIX 



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 



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 



OCTOBER-NOVEMBER, 191 1 



CONTENTS 



THE IOW AN DRIFT ------------------- Samuel Calvin 577 



THE THEORY OF ISOSTASY ---------------- Harmon Lewis 603 



SPECULATIONS REGARDING THE GENESIS OF THE DIAMOND Orvelle A. Derby 627 



PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. IV - - -S. Kozu 632 



FACTORS INFLUENCING THE ROUNDING OF SAND GRAINS - - Victor Ziegler 645 



THE UNCONFORMITY BETWEEN THE BEDFORD AND BEREA FORMATIONS OF 



NORTHERN OHIO ------------- Wilbur Greeley Burroughs 655 



EDITORIAL ------------------------. T. C. C. 660 



REVIEWS ----------------------------- 661 



RECENT PUBLICATIONS ----------------------- 669 



C^e flSuifcetgit? of Chicago $re$$ 



CHICAGO, ILLINOIS 



Agents : 



THE CAMBRIDGE UNIVERSITY PRESS, London and Edinburgh 



WILLIAM WESLEY & SON, London 



TH. STAUFFER, Leipzig 



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



