THE 
SURNAL OF GEOLOGY 
A Semi-Quarterly Magazine of Geology and 
Related Sciences 
EDITORS 
Tuomas C, CHAMBERLIN, 72 General Charge; Roun D, Satispury, Geographic Geology; 
SamMuEL W. Wiuiston, Vertebrate Paleontology; StTuART WELLER, Jnvertebrate Paleontology, 
ALBERT JOHANNSEN, Petrology; WaLLAcE W. Atwoop, Physiography; Wittiam H. Emmons, 
Economic Geology; Rotiin T. CHAMBERLIN, Dyxametc Geology. 
ASSOCIATE EDITORS 
Srrk ARCHIBALD GEIKIE, Great Britain; HEINRICH ROSENBUSCH, Germany; THEODOR N. 
TSCHERNYSCHEW, Aussza,; CHARLES Barrois, /ranxce; ALBRECHT PENCK, Germany; Hans 
Reuscu, Vorway,; GERARD DE GEER, Sweden; ORvILLE A, Derby, Brazzl; T, W. EpGEwortH 
Davin, Australia; Baitey Witus, Argentine Republic; Grove K. GILBERT, Washington, D.C.; 
Cuares D, WALcott, Swzthsontan Institution; HENRY S. WILLIAMS, Cornell University; JOSEPH 
P. Ippines, Washington, D.C.; Joun C. BRANNER, Leland Stanford Juntor University; 
Ricuarp A. F. PENROSE, Jr., Phzladelphia, Pa.; WitutaM B. CLarK, Johns Hopkins University; 
Wiriiam H. Hoses, University of Michigan; FRANK D, Apvams, MeGzll University; CHARLES 
K, Leitu, Untverszty of Wisconsin. 
; _ VOLUME XxX 
JANUARY-DECEMBER, 10912 
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‘ THE UNIVERSITY OF CHICAGO PRESS 
CHICAGO, ILLINOIS 
