IRON  AND  MANGANESE. 
During  the  past  year  special  attent  ion  has  been  attracted  to  the  American  iron  industry, 
both  by  its  remarkably  prosperous  condition  and  also  by  the  publicity  which  has  been 
given  to  attempts  to  effect  a  merger  of  important  southern  iron  interests.  Another  feature 
worthy  of  note  has  been  the  commencement  of  active  exploration  work  on  western  iroo 
deposits.  In  both  these  fields  the  Survey  has  taken  up  detailed  work  during  1905,  and 
preliminary  reports  on  the  results  of  some  of  this  work  are  presented  in  the  following 
papers: 
THE  CLINTON  OR  RED  ORES  OF  NORTHERN  ALABAMA. 
By  Edwin  C.  Eckel. 
Introduction. — During  the  fall  of  L905  detailed  work  was  commenced  on  the  iron  ores  of 
Alabama.  The  Clinton  or  wi\  ores  were  examined  in  the  district  along  the  flanks  of  Lookout 
Mountain,  from  the  Georgia  line  to  At  t  alia  and  Gadsden;  and  the  brown  ores  of  the  Annistclj 
and  Talladega  districts  were  also  surveyed.  The  present  preliminary  report  contains  notes' 
on  the  developments  in  the  red-ore  districts  covered. 
In  view  of  the  practical  importance  of  the  subjects,  descriptions  of  the  ores  of  this  district  i 
will  be  prefaced  by  brief  notes  on  the  origin  and  character  of  the  red  ores  ift  general. 
i 
ORIGIN   AND   CHARACTER  OF  THE  CLINTON   ORES. 
THEORIES    OF    ORIGIN. 
For  many  years  the  origin  of  the  oolil  ic  and  fossil  ores  which  occur  in  rocks  of  "Clinton' 
age  has  been  a  much  discussed  subject.     Minor  points  of  difference  being  disregarded, 
may  be  said  that  the  various  theories  which  have  been  advanced  to  account  for  the  origi 
of  these  ores  can  be  reduced  to  two.     These  two  opposing  theories  arc,  briefly  stated,  a 
follows: 
(1)  Original  deposition. — The  ores  were  formed  at  the  same  time  as  the  rocks  whicl 
inclose  them,  having  been  deposited  in  a  sea  or  basin  along  with  the  sandstones  and  shale 
which  now  accompany  them. 
(2)  Replacement. — The  ores  are  of  much  later  origin  than  their  inclosing  rocks,  havin; 
been  formed  by  the  replacement  of  original  beds  of  limestone  by  iron  brought  in  by  per 
eolating  waters. 
PRACTICAL    IMPORTANCE    OF   THE   QUESTION. 
In  addition  to  the  <|iiestioiis  ()f  purely  geologic  interest  which  are  connected  with  th 
differences  of  opinion  as  to  the  origin  of  the  Clinton  ores,  the  matter  has  a  very  distinc 
practical  bearing  on  the  working  of  the  ores.  This  phase  of  the  subject  may  be  stated  a 
follows: 
If  the  ore  deposits  are  due  to  the  replacement  of  a  limestone  we  can  expect  them  t 
rapidly  decrease  in  value  with  depth,  becoming  lower  in  iron  and  higher  in  lime,  until  a 
no  great  depth  the  bed  will  consist  entirely  of  unaltered  limestone. 
If,  on  the  contrary,  the  ore  deposits  are  original,  no  such  regular  decrease  in  richness  i 
to  be  expected  as  the  mines  are  driven  deeper.  Patches  of  low-grade  ore  may  be  struct 
but  these  will  be  due  to  original  differences  in  the  richness  of  the  ore,  and  a  slope  migh 
pass  downward  through  such  a  patch  of  lean  ore  into  another  zone  of  high-grade  ore. 
J  71' 
