VOLUME XXXI NUMBER i 



THE 



Journal of Geology 



A Semi-Quarterly 



Edited By 

 . thomas c. chamberlin 



With the Active Collaboration of 



ROLLIN T. CHAMBERLIN, Mamging Editor 

 Dynamic Geology 

 STUART WELLER, Invertebrate Paleontology ALBERT JOHANNSEN, Petrology 



EDSON S. BASTIN, Economic Geology J. HARLEN BRETZ, Stratigraphic Geology 



ASSOCIATE EDITORS 



SIR ARCHIBALD GEIKIE, Great Britain CHARLES D. WALCOTT, Smithsonian Institution 



CHARLES BARROIS, France » DAVID WHITE, U.S. Geological Survey 



ALBRECHT PENCK, Germany ^ RICHARD A.jF. PENROSE, Jr., Philadelphia, Pa. 



HANS REUSCH, Norway WILLIAM H. HOBBS, University of Michigan 



GERARD DeGEER, Sweden FRANK D. ADAMS, McGill University 



SIR T. W. EDGEWORTH DAVID, Australia CHARLES K. LEITH, University of Wisconsin 



H. A. BROUWER, Polytechnic University, Delft, Holland WALLACE W. ATWOOD, Clark University 



BAILEY WILLIS, Leland Stanford Junior University WILLIAM H. EMMONS, University of Minnesota 



ARTHUR L. DAY, Carnegie Institution 



JANUARY-FEBRUARY 1923 



THE CYCLE OF EROSION AND THE SUMMIT LEVEL OF THE ALPS - W. M. Davis i 



SOME NEW FEATURES IN THE PHYSIOGRAPHY AND GEOLOGY OF GREENLAND 



Lauge Koch 42 



THE LAVA FIELD OF THE PARANA BASIN, SOUTH AMERICA Charles Laurence Baker 66 



PETROLOGICAL ABSTRACTS AND REVIEWS - - - 80 



REVIEWS - - . 86 



THE UNIVERSITY OF CHICAGO PRESS 



CHICAGO, ILLINOIS, U.S.A. 



THE CAMBRIDGE UNIVERSITY PRESS, London 



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



THE MISSION BOOK COMPANY, Shanghai 



