Wels, 
foURNAIL OF GEOLOGY 
A Semi-Quarterly Magazine of Geology and 
elated “Sciences 
EDITORS 
T. C. CHAMBERLIN, 2x General Charge 
R. D. SALISBURY : ROA She RENIK@ Si ine 
Geographic Geology Economic Geology 
J. P. IDDINGS Cc. R. VAN HISE 
Petrology Structural Geology 
STUART WELLER W. H. HOLMES 
Paleontologic Geology Anthropic Geology 
S. W. WILLISTON, Vertebrate Paleontology 
ASSOCIATE EDITORS 
SIR ARCHIBALD GEIKIE_ . G. K. GILBERT 
Great Britain Washington, D. C. 
H. ROSENBUSCH H. S. WILLIAMS 
Germany Cornell University 
CHARLES BARROIS CLD WALCOLE 
France U.S. Geological Survey 
ALBRECHT PENCK J. C. BRANNER 
Germany Stanford University 
HANS REUSCH W. B. CLARK 
. Norway - Johns Hopkins University 
GERARD DE GEER Oo. A. DERBY 
Sweden i Brazil 
Ao Wits Ee) AVA) 
Australia 
VOLUME. XVII 
CHICAGO 
The Anibersity ot Chicago Press 
