THE Nie.‘ 
JOURNAL OF GEOLOGY 
A Semi-Quarterly Magazine of Geology and 
Related Sciences 
EDITED BY 
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY 
With the Active Collaboration of 
*SAMUEL W. WILLISTON ALBERT JOHANNSEN 
Vertebrate Paleontology Petrology 
STUART WELLER ROLLIN T. CHAMBERLIN 
Invertebrate Paleontology Dynamic Geology 
ALBERT D. BROKAW, Economic Geology 
ASSOCIATE EDITORS 
SIR ARCHIBALD GEIKIE, Great Britain *HENRY S. WILLIAMS, Cornell University 
CHARLES BARROIS, France JOSEPH P. IDDINGS, Washington, D.C. 
ALBRECHT PENCK, Germany fe JOHN C. BRANNER, Leland Stanford Junior Uni- 
HANS REUSCH, Norway versity 
GERARD DEGEER, Sweden RICHARD A. F. PENROSE, Jr., Philadelphia, Pa. 
T. W. EDGEWORTH DAVID, Australia WILLIAM H. HOBBS, University of Michigan 
BAILEY WILLIS, Leland Stanford Junior FRANK D. ADAMS, McGill University 
University CHARLES K. LEITH, University of Wisconsin” 
*GROVE K. GILBERT, Washington, D.C. WALLACE W. ATWOOD, Harvard University 
CHARLES D. WALCOTT, Smithsonian WILLIAM H. EMMONS, University of Minnesota 
Institution ARTHUR L. DAY, Carnegie Institution 
*Deceased 
VOLUME XXVI 
JANUARY-DECEMBER, 10918 
THE UNIVERSITY OF CHICAGO PRESS 
CHICAGO, ILLINOIS 
