﻿462 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  noticeably 
  at 
  the 
  western 
  end 
  the 
  rock 
  assumes 
  a 
  brownish 
  

   red 
  color. 
  As 
  a 
  whole 
  it 
  may 
  be 
  said 
  that 
  the 
  stone 
  is 
  very 
  pure 
  

   and 
  where 
  shale 
  impurities 
  occur 
  they 
  are 
  generally 
  in 
  the 
  shape 
  

   of 
  horses 
  which 
  can 
  be 
  easily 
  separated 
  in 
  the 
  mining 
  of 
  the 
  

   rock. 
  The 
  following 
  analysis 
  indicates 
  very 
  well 
  the 
  high 
  de- 
  

   gree 
  of 
  purity 
  of 
  this 
  material: 
  

  

  Silica 
  70 
  

  

  Alumina 
  -. 
  1.00 
  

  

  Ferric 
  oxid 
  .70 
  

  

  Lime 
  53.90 
  

  

  Magnesia 
  1 
  . 
  40 
  

  

  Carbon 
  dioxid 
  42.50 
  

  

  100.20 
  

   Westchester 
  county 
  

  

  The 
  limestones 
  in 
  this 
  county 
  are 
  all 
  of 
  the 
  same 
  age, 
  probably 
  

   Trenton-Calciferous. 
  They 
  extend 
  across 
  the 
  county 
  in 
  a 
  north- 
  

   easterly 
  direction 
  forming 
  several 
  well 
  marked 
  belts 
  which 
  either 
  

   border 
  or 
  underlie 
  the 
  main 
  valleys. 
  The 
  two 
  most 
  important 
  

   ones 
  are 
  those 
  along 
  the 
  line 
  of 
  the 
  Harlem 
  R. 
  R. 
  and 
  the 
  North- 
  

   ern 
  R. 
  R. 
  The 
  former 
  has 
  been 
  extensively 
  opened 
  up 
  at 
  Tucka- 
  

   hoe 
  and 
  Pleasantville 
  and 
  so 
  far 
  as 
  examined 
  contains 
  the 
  better 
  

   grade 
  of 
  stone. 
  

  

  A 
  third 
  important 
  area 
  occurs 
  south 
  of 
  Sing 
  Sing. 
  Other 
  oc- 
  

   currences 
  are 
  northwest 
  of 
  Peekskill, 
  near 
  Somers, 
  Amawalk 
  and 
  

   Hastings. 
  

  

  The 
  limestones 
  in 
  this 
  county 
  are 
  often 
  highly 
  magnesian, 
  

   coarse 
  to 
  fine 
  grained 
  metamorphosed 
  rocks. 
  At 
  times 
  they 
  are 
  

   exceptionally 
  free 
  from 
  silica. 
  

  

  There 
  are 
  two 
  important 
  quarries 
  at 
  Sing 
  Sing, 
  the 
  one 
  be- 
  

   longing 
  to 
  Henry 
  Marks 
  the 
  other 
  to 
  the 
  Sing 
  Sing 
  lime 
  co. 
  The 
  

   stone 
  in 
  Mr 
  Marks's 
  quarry 
  is 
  finely 
  granular 
  and 
  slightly 
  grayish 
  

   in 
  tint 
  while 
  the 
  best 
  stone 
  in 
  the 
  Sing 
  Sing 
  lime 
  co.'s 
  quarry 
  

   is 
  white 
  and 
  coarse 
  grained 
  but 
  possesses 
  a 
  high 
  degree 
  of 
  

   purity. 
  

  

  