x 
Volume XVII Number 7 
THE 
Journal of Geology 
A Semi-Quarterly Magazine of Geology and 
Related Sciences 
OCTOBER-NOVEMBER, 17909 
EDITORS 
T. C. CHAMBERLIN, zz General Charge 
R. D. SALISBURY R. A. F. PENROSE 
Geographic Geology Economic Geology 
J. P. IDDINGS C. 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 O. A. DERBY 
Great Britain Brazil 
H. ROSENBUSCH G. K. GILBERT 
Germany Washington, D. C. 
CHARLES BARROIS H. S. WILLIAMS 
; France Cornell University 
ALBRECHT PENCK : Cc. D. WALCOTT 
Germany Smithsonian Institution 
HANS REUSCH j J. C. BRANNER 
Norway Stanford University 
GERARD DE GEER W. B. CLARK 
Sweden Johns Hopkins University 
T. W. E. DAVID WILLIAM H. HOBBS 
Australia University of Michigan 
TH. TSCHERNYSCHEW, Russia 
The Anibvbersity of Chicago Press 
CHICAGO AND NEW YORE 
Wittiam WeEsLEY & Son, Lonpon 
