THE 



JOURNAL OF GEOLOGY 



A Semi-Quarterly Magazine of Geology and 

 Related Sciences 



Editors 



T. C. CHAMBERLIN, in General Charge 

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



Geographic Geology Economic Geology 



J. P. IDDINGS C. R. VAN HISE 



Petrology ' Structtiral Geology 



STUART WELLER W. H. HOLMES 



Paleontologic Geology Anthropic Geology 



S. W. WILLISTON, Vertebrate Paleontology 



Associate Editors 



CHICAGO 



1906 



