﻿IRON 
  ORES 
  OF 
  THE 
  CLINTON 
  FORMATION 
  49 
  

  

  form 
  clay 
  and 
  amounts 
  to 
  some 
  2 
  or 
  3^ 
  as 
  a. 
  rule. 
  The 
  lime 
  and 
  

   magnesia 
  are 
  due 
  to 
  limestone 
  which 
  occurs 
  as 
  a 
  cementing 
  ma- 
  

   terial 
  or 
  as 
  unreplaced 
  fossil 
  fragments. 
  They 
  are 
  in 
  largest 
  quan- 
  

   tity 
  in 
  the 
  fossil 
  ores 
  where 
  the 
  carbonates 
  average 
  from 
  15 
  to 
  20^. 
  

   The 
  oolitic 
  ores 
  carry 
  about 
  10 
  or 
  12$ 
  of 
  carbonates 
  as 
  a 
  rule. 
  

  

  Origin 
  of 
  the 
  Clinton 
  ores 
  

  

  The 
  subject 
  of 
  the 
  derivation 
  of 
  the 
  hematites, 
  which 
  are 
  so 
  con- 
  

   stant 
  an 
  accompaniment 
  of 
  the 
  Clinton 
  formation, 
  has 
  been 
  re- 
  

   peatedly 
  discussed 
  in 
  the 
  literature 
  relating 
  to 
  the 
  geology 
  of 
  the 
  

   different 
  fields. 
  There 
  is 
  more 
  than 
  scientific 
  interest 
  involved 
  in 
  the 
  

   question, 
  since 
  the 
  mode 
  of 
  origin 
  has 
  -a 
  bearing 
  upon 
  the 
  distri- 
  

   bution 
  of 
  the 
  deposits 
  and 
  its 
  determination 
  is 
  desirable 
  as 
  an 
  aid 
  

   to 
  exploration. 
  It 
  has 
  become 
  quite 
  evident 
  with 
  the 
  progress 
  of 
  

   investigations 
  that 
  there 
  is 
  a 
  great 
  degree 
  of 
  uniformity 
  in 
  the 
  

   character 
  and 
  manner 
  of 
  occurrence 
  of 
  the 
  Clinton 
  ores 
  throughout 
  

   their 
  extent 
  and 
  that 
  they 
  have 
  been 
  formed 
  in 
  most, 
  if 
  not 
  all, 
  

   cases 
  under 
  similar 
  conditions. 
  

  

  Of 
  the 
  many 
  principles 
  that 
  are 
  known 
  to 
  govern 
  the 
  accumula- 
  

   tion 
  of 
  iron 
  ores 
  in 
  their 
  varied 
  development, 
  it 
  is 
  possible 
  to 
  elimi- 
  

   nate 
  all 
  but 
  a 
  few 
  as 
  having 
  no 
  conceivable 
  relation 
  to 
  the 
  Clinton 
  

   hematites. 
  In 
  fact 
  there 
  are 
  but 
  two 
  explanations 
  which 
  have 
  re- 
  

   ceived 
  the 
  attention 
  of 
  geologists 
  and 
  need 
  to 
  be 
  considered 
  here. 
  

  

  According 
  to 
  the 
  first 
  view, 
  originally 
  advanced 
  by 
  James 
  Hall 
  

   in 
  his 
  description 
  of 
  the 
  Clinton 
  formation 
  in 
  western 
  New 
  York, 
  

   the 
  ores 
  were 
  formed 
  in 
  standing 
  water 
  at 
  the 
  same 
  time 
  as 
  the 
  

   inclosing 
  beds. 
  Hall 
  further 
  expresses 
  the 
  belief 
  that 
  the 
  source 
  of 
  

   the 
  iron 
  is 
  to 
  be 
  found 
  in 
  the 
  bodies 
  of 
  iron 
  oxids 
  and 
  pyrite 
  con- 
  

   tained 
  in 
  the 
  old 
  crystalline 
  rocks. 
  Thermal 
  waters 
  are 
  considered 
  

   to 
  have 
  been 
  influential 
  in 
  the 
  deposition 
  of 
  the 
  oolitic 
  ore 
  and 
  they 
  

   may 
  have 
  hastened 
  the 
  decomposition 
  of 
  the 
  pyrite. 
  These 
  con- 
  

   clusions 
  were 
  generally 
  adopted 
  by 
  the 
  early 
  writers. 
  

  

  The 
  alternative 
  explanation, 
  proposed 
  by 
  Shaler 
  for 
  the 
  Clinton 
  

   ores 
  in 
  Kentucky 
  and 
  favored 
  by 
  some 
  geologists 
  for 
  the 
  whole 
  as- 
  

   semblage 
  of 
  Clinton 
  ores, 
  regards 
  the 
  hematite 
  as 
  a 
  secondary 
  intro- 
  

   duction 
  after 
  the 
  formation 
  had 
  been 
  upraised 
  above 
  sea 
  level. 
  The 
  

   ore 
  beds 
  are 
  considered 
  to 
  be 
  replacements 
  of 
  original 
  limestones, 
  

   effected 
  by 
  the 
  circulation 
  of 
  ground 
  waters 
  which 
  leached 
  the 
  

   ferruginous 
  constituents 
  from 
  the 
  overlying 
  strata. 
  This 
  theory 
  

   of 
  replacement 
  has 
  found 
  its 
  principal 
  advocates 
  among 
  geologists 
  

  

  