Volume XVIII 



Number 4 



THE 



Journal of Geology 



A Semi -Quarterly flagazine of Geology and 

 Related Sciences 



MAY- JUNE, iqio 



EDITORS 



T. C. CHAM BERLIN, in General Charge 



R. D. SALISBURY 



Geographic Geology 

 J. P. IDDINGS 



Petrology 

 STUART WELLER 



Paleontologic Geology 



R. A. F. PENROSE 



Economic Geology 

 C. R. VAN HISE 



Structural Geology 

 W. H. HOLMES 



Anthropic Geology 



S. W. WILLISTON, Vertebrate Paleontology 



ASSOCIATE EDITORS 



SIR ARCHIBALD GEIKIE 



Great Britain 

 H. ROSENBUSCH 



Germany 

 CHARLES BARROIS 



France 

 ALBRECHT PENCK 



Germany 

 HANS REUSCH 



Norway 



GERARD DE GEER 

 Sweden 



T. W. E. DAVID 



Australia 



O. A. DERBY 



Brazil 

 G. K. GILBERT 



Washington, D. C. 

 H. S. WILLIAMS 



Cornell University 

 C. D. WALCOTT 



Smithsonian Institution 

 J. C. BRANNER 



Stanford University 

 W. B. CLARK 



Johns Hopkins University 

 WILLIAM H. HOBBS 



University of Michigan 



TH. TSCHERNYSCHEW, Russia 



Ei)e SanibcrgitB of arf)icagti ^^ress 



CHICAGO AND NEW YORK 

 William Wesley & Son, Loni>on 



