VOLUME XXV 



THE 



NUMBER 3 



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 ALBERT JOHANNSEN, Petrology 



STUART WELLER, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology 



ALBERT D. BROKAW, Economic 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 



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 

 WALLACE W. ATWOOD, Harvard University 

 WILLIAM H. EMMONS, University of Minnesota 

 ARTHUR L. DAY, Carnegie Institution 



APRIL-MAY 1917 



THE PROBLEM OF THE ANORTHOSITES - N. L. Bowen 200 



THE MIDDLE PALEOZOIC STRATIGRAPHY OF THE CENTRAL ROCKY MOUNTAIN 



REGION. II - C. W. Tomlinson 244 



A FEW INTERESTING PHENOMENA ON THE ERUPTION OF USU - Y. Oinouye 258 



INTRAFORMATIONAL PEBBLES IN THE RICHMOND GROUP, AT WINCHESTER, 



OHIO ..-- August F. Foerste 289 



REVIEWS - - 307 



THE 



UNIVERSITY OF CHICAGO 



CHICAGO, ILLINOIS, U.S.A. 



PRESS 



Agents : 



THE CAMBRIDGE UNIVERSITY PRESS, London and Edinburgh 



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



THE MISSION BOOK COMPANY, Shanghai 



