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Ler N AL Or GEOLOGY 
A Semi-Quarterly Magazine of Geology and 
Relateds: Scrences 
EpIToRS 
T. C. CHAMBERLIN, zz General Charge 
R. D. SALISBURY Rk. A. BE. PENROSE, Jr: 
Geographic Geology Liconomic Geology 
J. P. IDDINGS CR. VAN HIS 
Petrology Pre-Cambrian Geology 
STUART WELLER We Ee HOLMES 
Paleontologic Geology Anthropic Geology 
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 Vale University 
ALBRECHT PENCK JOSEPH LE CONTE 
Austria University of California 
HANS REUSCH Cs IDs WAILICOI I 
Norway U.S. Geological Survey 
GERARD DE GEER J. C. BRANNER 
Sweden Stanford University 
GEORGE M. DAWSON iE Gy RUSSHE 
Canada University of Michigan 
WILLIAM B. CLARK, Johns Hopkins University 
fF isonian Insitaygs 
(250422 
VOEUMEE V Ill \ 
Sonal Muses 
GHICAGO 
The Wnibversity of Chicago Press 
19g00 
