﻿ECONOMIC 
  GEOLOGY 
  321 
  

  

  also 
  in 
  large 
  d'eposits, 
  wliicli 
  are 
  associated 
  with 
  ochreous 
  clays, 
  

   and 
  in 
  some 
  cases^ 
  with 
  a 
  gray 
  carbonate 
  of 
  iron, 
  in 
  beds 
  under- 
  

   lying 
  it. 
  These 
  ore 
  bodies 
  are 
  wholly 
  in 
  the 
  limestone 
  or 
  between 
  

   the 
  limestone 
  and 
  the 
  adjacent 
  slate 
  or 
  schist 
  formations, 
  or 
  they 
  

   are 
  in 
  the 
  latter, 
  and 
  as 
  a 
  rule 
  of 
  occurrence 
  they 
  are 
  found 
  on 
  or 
  

   near 
  the 
  dividing 
  line 
  between 
  these 
  formations. 
  Near 
  Fishkill 
  

   and 
  at 
  Shenandoah 
  the 
  deposits 
  are 
  at 
  the 
  border 
  of 
  the 
  Cam- 
  

   brian 
  sandstone 
  and 
  at 
  the 
  foot 
  of 
  the 
  Archaean 
  ridges. 
  The 
  

   existence 
  of 
  the 
  carbonate 
  ore 
  in 
  the 
  deeper 
  parts 
  of 
  some 
  of 
  the 
  

   mines 
  and 
  interstratified 
  with 
  the 
  limestones 
  is 
  suggestive 
  of 
  the 
  

   origin 
  of 
  the 
  oxide 
  (limonite) 
  by 
  the 
  decomposition 
  of 
  the 
  fer- 
  

   riferous 
  beds 
  through 
  oxidation 
  and 
  the 
  agency 
  of 
  carbonated 
  

   waters, 
  and 
  of 
  the 
  great 
  masses 
  of 
  colored 
  clays, 
  also, 
  through 
  

   the 
  disintegration 
  and 
  decay 
  of 
  the 
  slaty 
  rocks 
  and 
  more 
  argil- 
  

   laceous 
  limestone. 
  The 
  limestone 
  of 
  these 
  valleys 
  and 
  the 
  over- 
  

   lying 
  slaty 
  rocks 
  have 
  been 
  studied 
  by 
  Prof. 
  Dana, 
  and 
  are 
  re^ 
  

   ferred 
  by 
  him 
  to 
  the 
  Trenton 
  limestone 
  and 
  the 
  Hudson 
  river 
  

   slate 
  formations. 
  

  

  The 
  ore 
  occurs, 
  (1) 
  in 
  large 
  masses, 
  somewhat 
  cellular, 
  having 
  

   the 
  interstices 
  filled 
  with 
  clays 
  or 
  sandy 
  earths, 
  (2) 
  in 
  cavernous 
  

   and 
  hollow 
  ^ 
  bombs 
  ' 
  often 
  with 
  beautiful 
  mammillary 
  or 
  stalac- 
  

   titic 
  incrustations 
  on 
  the 
  interior, 
  and, 
  (3) 
  in 
  irregularly 
  shaped, 
  

   fragmentary 
  masses, 
  distributed 
  unevenly 
  through 
  the 
  ochreouB 
  

   clays 
  {' 
  ochres 
  ') 
  and 
  sandy 
  earths. 
  

  

  The 
  earliest 
  iron 
  manufacture 
  in 
  the 
  state 
  was 
  in 
  Columbia 
  

   county, 
  on 
  Ancram 
  creek, 
  and 
  was 
  probably 
  on 
  these 
  ores. 
  

  

  THE 
  LIMONITES 
  OF 
  STATEN 
  ISLAND 
  

  

  The 
  group 
  of 
  iron 
  mines 
  on 
  Staten 
  Island 
  is 
  in 
  a 
  superficial 
  

   deposit 
  probably 
  derived 
  from 
  the 
  underlying 
  rock 
  in 
  the 
  process 
  

   of 
  decomposition 
  which 
  has 
  produced 
  the 
  serpentine 
  of 
  that 
  

   region. 
  

  

  THE 
  CARBONATE 
  ORES 
  OF 
  THE 
  HUDSON 
  RIVER 
  

  

  The 
  mines 
  of 
  spathic 
  iron 
  ore, 
  or 
  carbonate 
  ore, 
  are 
  in 
  the 
  

   valley 
  of 
  the 
  Hudson 
  river, 
  in 
  Columbia 
  county, 
  south 
  of 
  the 
  city 
  

   of 
  Hudson, 
  and 
  in 
  Ulster 
  county 
  near 
  Napanoch. 
  The 
  mines 
  

  

  