﻿IRON 
  ORES 
  OF 
  THE 
  CLINTON 
  FORMATION 
  1 
  5 
  

  

  the 
  extraction 
  of 
  salt. 
  Their 
  presence, 
  even 
  if 
  not 
  due 
  to 
  included 
  

   beds 
  of 
  rock 
  salt, 
  which 
  so 
  far 
  have 
  never 
  been 
  discovered, 
  indicates 
  

   a 
  high 
  degree 
  of 
  salinity 
  for 
  the 
  waters, 
  that 
  is 
  likely 
  to 
  have 
  been 
  

   brought 
  about 
  by 
  evaporation 
  in 
  basins 
  shut 
  off 
  from 
  free 
  communi- 
  

   cation 
  with 
  the 
  sea. 
  The 
  deposition 
  of 
  the 
  Clinton 
  hematites 
  required 
  

   a 
  similar 
  concentration, 
  as 
  will 
  be 
  explained 
  later 
  in 
  the 
  discussion 
  

   of 
  their 
  origin. 
  

  

  The 
  existence 
  of 
  shallow 
  waters, 
  sheltered 
  bays 
  and 
  lagoons 
  re- 
  

   quisite 
  to 
  the 
  accumulation 
  of 
  deposits 
  like 
  those 
  characteristic 
  of 
  

   the 
  Clinton 
  formation 
  may 
  be 
  considered 
  as 
  indicative 
  of 
  an 
  exten- 
  

   sive 
  coastal 
  plain 
  stretching 
  southward 
  from 
  the 
  ancient 
  land 
  masses 
  

   — 
  the 
  Laurentian 
  and 
  Adirondack 
  areas. 
  Such 
  a 
  coastal 
  plain 
  had 
  

   been 
  built 
  up 
  from 
  wash 
  of 
  the 
  lands 
  during 
  the 
  long 
  interval 
  from 
  

   Potsdam 
  to 
  Medina 
  time. 
  During 
  the 
  Medina 
  age 
  there 
  must 
  have 
  

   been 
  a 
  gradual 
  sinking 
  of 
  this 
  platform 
  with 
  the 
  progress 
  of 
  sedi- 
  

   mentation, 
  and 
  the 
  subsidence 
  continued 
  into 
  Clinton 
  time, 
  though 
  

   not 
  on 
  the 
  same 
  scale. 
  

  

  As 
  to 
  the 
  northern 
  limits 
  of 
  the 
  shore 
  line 
  during 
  Clinton 
  time, 
  

   there 
  is 
  little 
  information 
  to 
  be 
  gained 
  from 
  present 
  conditions. 
  

   Since 
  the 
  uplifting 
  of 
  the 
  strata, 
  they 
  have 
  been 
  continuously 
  sub- 
  

   jected 
  to 
  erosion 
  and 
  their 
  outcropping 
  portions 
  worn 
  back 
  until 
  

   they 
  are 
  now 
  considerably 
  south 
  of 
  the 
  original 
  limits. 
  It 
  seems 
  

   scarcely 
  probable, 
  however, 
  that 
  the 
  Clinton 
  beds 
  ever 
  extended 
  so 
  

   far 
  north 
  as 
  to 
  overlap 
  on 
  the 
  crystallines, 
  since 
  this 
  would 
  involve 
  

   the 
  removal 
  of 
  more 
  than 
  100 
  miles 
  of 
  rock 
  on 
  the 
  western 
  end 
  of 
  

   the 
  belt, 
  between 
  the 
  present 
  line 
  of 
  outcrop 
  and 
  the 
  southern 
  edge 
  

   of 
  the 
  Canadian 
  Precambrie 
  area. 
  

  

  The 
  materials 
  of 
  which 
  the 
  Clinton 
  strata 
  are 
  composed 
  were 
  

   derived 
  ultimately 
  from 
  the 
  Precambrie 
  crystallines. 
  A 
  small 
  por- 
  

   tion 
  may 
  have 
  been 
  furnished 
  by 
  the 
  Paleozoic 
  sediments 
  fringing 
  

   the 
  crystalline 
  areas 
  and 
  previously 
  upraised 
  above 
  sea 
  level. 
  But 
  

   as 
  these 
  sediments 
  are 
  for 
  the 
  most 
  part 
  low 
  in 
  iron, 
  it 
  is 
  to 
  the 
  

   Precambrie 
  gneisses 
  and 
  schists 
  with 
  their 
  relatively 
  high 
  iron 
  con- 
  

   tent 
  and 
  extensive 
  iron 
  ore 
  deposits 
  that 
  we 
  must 
  look 
  for 
  the 
  source 
  

   of 
  the 
  Clinton 
  hematites. 
  The 
  only 
  sedimentary 
  strata 
  of 
  the 
  lower 
  

   Paleozoic 
  that 
  contain 
  appreciable 
  percentages 
  of 
  iron 
  are 
  the 
  Me- 
  

   dina 
  and 
  Potsdam 
  sandstones. 
  The 
  crystalline 
  rocks, 
  on 
  the 
  other 
  

   hand, 
  uniformly 
  carry 
  several 
  per 
  cent 
  of 
  iron 
  oxids, 
  both 
  free 
  as 
  

   magnetite 
  and 
  combined 
  in 
  the 
  silicate 
  minerals, 
  and 
  in 
  the 
  Adiron- 
  

   dack 
  region 
  they 
  inclose 
  important 
  bodies 
  of 
  magnetite, 
  hepatite 
  and 
  

   pyrite. 
  

  

  