V 



THE 



JOURNAL OF GEOLOGY 



A Semi-Quarterly Magazine of Geology and 

 Related Sciences 



Editors 

 t. c. chamberlin 



R. D. SALISBURY R. A. F. PENROSE, Jr. 



Geographic Geology Economic Geology 



J. P. IDD1NGS C. R. VAN HISE 



Petrology Pre- Cambrian Geology 



W. H. HOLMES, Anthropic Geology 



Associate Editors 



SIR ARCHIBALD GEIKIE 



Great Britain 

 H. ROSENBUSCH 



Germany 

 CHARLES BARROIS 



France 

 ALBRECHT PENCK 



Austria 

 HANS REUSCH 



Norway 

 GERARD DE GEER 



Sweden 

 GEORGE M. DAWSON 



Canada 



JOSEPH LE CONTE 



University of California 

 C. D. WALCOTT 



U. S. Geological Survey 

 G. K. GILBERT 



Washington, D. C. 

 H. S. WILLIAMS 



Yale University 

 J. C. BRANNER 



Leland Stanford University 

 I. C. RUSSELL 



University of Michigan 

 WILLIAM B. CLARK 



Johns Hopkins University 



O. A. DERBY, Brazil 



VOLUME VI 



CHICAGO 



&i)e Bntbersiti) of (tffncago 



1898 



Xt8# 





