﻿LIMESTONES 
  OF 
  NEW 
  YORK 
  AND 
  THEIR 
  ECONOMIC 
  VALUE 
  443 
  

  

  - 
  According 
  to 
  Darton 
  the 
  Trenton 
  limestone 
  reaches 
  its 
  maxi- 
  

   mum 
  thickness 
  at 
  Fort 
  Plain 
  where 
  it 
  is 
  9 
  feet, 
  but 
  decreases 
  to 
  

   7 
  feet 
  at 
  St 
  Johnsville. 
  

  

  The 
  limestone 
  varies 
  somewhat 
  sometimes 
  being 
  massive 
  as 
  

   at 
  Tribeshill 
  and 
  at 
  others 
  shaiy. 
  In 
  the 
  Tribeshill 
  quarries 
  12 
  to 
  

   15 
  feet 
  of 
  massive 
  stone 
  are 
  exposed. 
  Other 
  exposures 
  are 
  seen 
  

   in 
  the 
  quarries 
  north 
  of 
  Amsterdam. 
  

  

  At 
  D. 
  C. 
  Hewitt's 
  quarry 
  one 
  mile 
  north 
  of 
  Amsterdam 
  the 
  

   Trenton 
  rock 
  has 
  been 
  used 
  for 
  lime. 
  In 
  the 
  upper 
  quarry 
  the 
  

   stone 
  is 
  coarse 
  grained 
  and 
  the 
  layers 
  in 
  upper 
  portion 
  of 
  the 
  

   quarry 
  are 
  quite 
  impure 
  and 
  shaly. 
  

  

  The 
  rock 
  in 
  this 
  upper 
  quarry 
  burns 
  to 
  a 
  brown 
  lime. 
  In 
  the 
  

   lower 
  quarry 
  which 
  is 
  just 
  below 
  Hewitt's 
  limekiln 
  the 
  stone 
  is 
  

   much 
  purer 
  and 
  more 
  massive 
  than 
  that 
  of 
  the 
  upper 
  quarry. 
  

   The 
  lower 
  layers 
  are 
  harder, 
  are 
  light 
  gray 
  and 
  are 
  said 
  to 
  make 
  

   a 
  whiter 
  lime. 
  Under 
  this 
  comes 
  a 
  bed 
  of 
  lime 
  rock 
  which 
  is 
  

   practically 
  non-slaking 
  and 
  seems 
  to 
  have 
  hydraulic 
  properties. 
  

   The 
  lime 
  made 
  at 
  this 
  quarry 
  is 
  fairly 
  white. 
  The 
  composition 
  

   of 
  the 
  lower 
  limestone 
  runs 
  : 
  

  

  Silica 
  6.13 
  

  

  Alumina 
  ... 
  .79 
  

  

  Ferric 
  oxid 
  .61 
  

  

  Lime 
  carbonate 
  88 
  . 
  49 
  

  

  Magnesium 
  carbonate 
  2.45 
  

  

  98.57 
  

   The 
  upper 
  beds 
  showed 
  8.92^ 
  of 
  insoluble 
  matter. 
  

  

  There 
  is 
  evidently 
  considerable 
  variation 
  in 
  the 
  upper 
  layer 
  as 
  

   a 
  comparison 
  of 
  the 
  foregoing 
  analysis 
  with 
  the 
  first 
  of 
  the 
  fol- 
  

   lowing 
  three 
  shows. 
  They 
  were 
  made 
  by 
  J. 
  M. 
  Sherrerd 
  and 
  pub- 
  

   lished 
  in 
  19th 
  annual 
  report, 
  U. 
  S. 
  geol. 
  survey, 
  pt 
  6. 
  

  

  Upper 
  layer 
  Intermed 
  Lower 
  

  

  Silica 
  1.25 
  3.82 
  5.68 
  

  

  Ferric 
  oxid 
  ) 
  rt 
  ~ 
  , 
  nn 
  n 
  „„ 
  

  

  A1 
  . 
  [ 
  3.00 
  1.08 
  2.76 
  

  

  Alumina 
  ) 
  

  

  Lime 
  52.78 
  52.46 
  52.12 
  

  

  Magnesia 
  None 
  None 
  None 
  

  

  Undet 
  (C0 
  2 
  ?)... 
  42.97 
  42.64 
  39.44 
  

  

  