﻿370 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  ping 
  in 
  a 
  belt 
  about 
  eight 
  miles 
  long 
  and 
  two 
  and 
  a 
  half 
  wide. 
  

   At 
  High 
  Falls 
  there 
  is 
  an 
  upper 
  bed 
  of 
  cement 
  15 
  feet 
  thick 
  and 
  

   a 
  lower 
  bed 
  five 
  feet 
  thick 
  separated 
  by 
  three 
  feet 
  of 
  impure 
  

   limestone. 
  At 
  Whiteport 
  the 
  upper 
  cement 
  bed 
  is 
  12 
  feet 
  thick, 
  

   the 
  lower 
  from 
  15 
  to 
  20 
  and 
  the 
  intervening 
  limestone 
  10 
  feet 
  in 
  

   thickness. 
  How 
  far 
  they 
  may 
  extend 
  under 
  the 
  overlying 
  rocks 
  to 
  

   the 
  westward 
  is 
  not 
  known 
  and 
  their 
  southern 
  termination 
  has 
  

   not 
  been 
  explored. 
  To 
  the 
  northeast 
  the 
  cement 
  thins 
  out 
  

   rapidly 
  and 
  gives 
  place 
  to 
  impure 
  cements 
  and 
  limestones, 
  but 
  

   it 
  thickens 
  again 
  rapidly 
  in 
  the 
  Eondout 
  region. 
  At 
  Kondout 
  

   there 
  are 
  two 
  cement 
  beds, 
  the 
  lower 
  one 
  is 
  22 
  feet 
  thick 
  and 
  the 
  

   upper 
  five 
  feet 
  thick 
  with 
  three 
  feet 
  of 
  limestone 
  and 
  cement 
  in- 
  

   tervening. 
  Northwest 
  the 
  lower 
  cement 
  bed 
  thins. 
  

  

  Origin 
  of 
  limestone 
  

  

  Most 
  limestones 
  are 
  of 
  marine 
  origin, 
  few 
  of 
  them 
  being 
  fresh- 
  

   water 
  deposits. 
  They 
  result 
  generally 
  from 
  the 
  accumulation 
  on 
  

   the 
  ocean 
  bottom, 
  of 
  the 
  calcareous 
  remains 
  of 
  marine 
  organ- 
  

   isms, 
  such 
  as 
  the 
  shells 
  of 
  mollusks, 
  the 
  cases 
  of 
  foraminifera, 
  

   skeletons 
  of 
  corals, 
  etc. 
  These 
  are 
  sometimes 
  plainly 
  apparent 
  

   in 
  the 
  limestone, 
  but 
  very 
  often 
  the 
  shells 
  become 
  comminuted 
  

   before 
  settling 
  on 
  the 
  ocean 
  bottom, 
  or 
  they 
  may 
  be 
  broken 
  by 
  the 
  

   pressure 
  of 
  other 
  material 
  deposited 
  on 
  them, 
  so 
  that 
  not 
  in- 
  

   frequently 
  limestones 
  show 
  no 
  trace 
  whatever 
  of 
  organic 
  re- 
  

   mains. 
  Limestones 
  of 
  great 
  purity 
  have 
  generally 
  been 
  de- 
  

   posited 
  in 
  the 
  deeper 
  portions 
  of 
  the 
  ocean, 
  far 
  enough 
  away 
  

   from 
  the 
  shore 
  to 
  prevent 
  their 
  contamination 
  by 
  siliceous 
  or 
  

   argillaceous 
  sediments 
  brought 
  down 
  to 
  the 
  sea 
  by 
  rivers. 
  The 
  

   varying 
  intermixture 
  of 
  such 
  classes 
  of 
  material 
  with 
  the 
  cal- 
  

   careous 
  mud 
  results 
  in 
  the 
  formation 
  of 
  all 
  grades 
  of 
  rock 
  be- 
  

   tween 
  a 
  limestone 
  and 
  sandstone 
  on 
  one 
  hand, 
  and 
  a 
  shale 
  on 
  

   the 
  other. 
  A 
  siliceous 
  limestone 
  is 
  one 
  with 
  siliceous 
  impurity, 
  

   which 
  if 
  the 
  silica 
  predominates 
  is 
  called 
  a 
  calcareous 
  sand- 
  

   stone. 
  In 
  the 
  same 
  way 
  we 
  may 
  have 
  a 
  shaly 
  or 
  argillaceous 
  

   limestone 
  or 
  a 
  calcareous 
  shale. 
  

  

  Limestone 
  may 
  also 
  be 
  formed 
  chemically, 
  viz, 
  by 
  the 
  deposi- 
  

   tion 
  of 
  a 
  calcareous 
  deposit 
  from 
  waters 
  having 
  carbonate 
  of 
  

   lime 
  in 
  solution. 
  

  

  