Bulletin  No.  285  Series  A,  Economic  Geology,  73 
DEPARTMENT  OF  THE   INTERIOR 
UNITED  STATES  GEOLOGICAL  SURVEY 
CHARLES  I).  WALCOTT,  Director 
CONTRIBUTIONS 
TO 
ECONOMIC  GEOLOGT 
T 
19  O  5 
S.  E.  EMMONS 
E.   C.  ECKEL 
Geologists   in    Charge 
WASHINGTON 
GOVERNMENT     PRINTING     OFFICE 
1906 
