7 
Series  A,  Economic  Geology,  73 
Bulletin  No.  285 
DEPARTMENT  OF  THE   INTERIOR 
UNITED  STATES  GEOLOGICAL  SURVEY 
CHARLES  B.  WALCOTT,  Director 
CONTRIBUTIONS 
TO 
lECONOMIC  GEOLOGY 
19  O  5 
S.  F.  EMMONS 
E.  O.ECKEL 
G-eologists   in.    Charge 
WASHINGTON 
GOVERNMENT    PRINTING     OFFICE 
1906 
