﻿160 
  NEW 
  TOEK 
  STATE 
  MUSEUM 
  

  

  loses 
  its 
  carbonate 
  of 
  lime 
  and 
  becomes 
  a 
  gritty 
  yellowish 
  sand- 
  

   stone. 
  It 
  is 
  found 
  only 
  from 
  Cberry 
  Valley 
  eastward, 
  extending 
  

   round 
  the 
  front 
  of 
  the 
  Helderbergs 
  and 
  along 
  the 
  hills 
  west 
  of 
  

   the 
  Hudson, 
  but 
  does 
  not 
  appear 
  to 
  be 
  known 
  in 
  Pennsylvania. 
  

  

  Upper 
  Helderberg 
  or 
  Corniferous 
  Limestone 
  

   This 
  which 
  lies 
  above 
  the 
  Schoharie 
  grit, 
  Cauda 
  galli 
  grit 
  and 
  

   Oriskany 
  sandstone, 
  and 
  where 
  these 
  are 
  wanting, 
  together 
  with 
  

   the 
  Lower 
  Helderberg, 
  as 
  in 
  western 
  New 
  York, 
  rests 
  immedia- 
  

   tely 
  on 
  the 
  waterlime 
  group, 
  is 
  one 
  of 
  the 
  most 
  widely 
  known 
  and 
  

   useful 
  limestones 
  of 
  the 
  state. 
  The 
  lower 
  portion, 
  from 
  10 
  to 
  20 
  

   feet 
  in 
  thickness, 
  is 
  generally 
  a 
  coarse-grained 
  crystalline 
  gray 
  

   rock, 
  and, 
  when 
  free 
  from 
  chert, 
  working 
  well 
  under 
  the 
  hammer 
  

   and 
  chisel, 
  and 
  often 
  taking 
  a 
  good 
  polish 
  as 
  a 
  marble. 
  It 
  is 
  

   called, 
  from 
  being 
  very 
  extensively 
  quarried 
  in 
  Onondaga 
  county, 
  

   the 
  Onondaga 
  Limestone. 
  It 
  is 
  easily 
  traced 
  from 
  near 
  Rondout 
  

   on 
  the 
  Hudson 
  to 
  the 
  Helderbergs 
  in 
  Albany 
  county, 
  where 
  its 
  

   outcropping 
  edge 
  turns 
  westward, 
  and 
  extends 
  past 
  Schoharie, 
  

   Cherry 
  Valley, 
  Bridgewater, 
  Oriskany 
  falls, 
  the 
  falls 
  of 
  the 
  Chit- 
  

   tenango 
  below 
  Cazenovia, 
  Split 
  Rock, 
  Auburn, 
  Phelps, 
  Le 
  Roy, 
  

   and 
  Williamsville 
  to 
  Black 
  Rock. 
  Through 
  nearly 
  all 
  this 
  dis- 
  

   tance 
  it 
  preserves 
  its 
  well 
  marked 
  character, 
  and 
  is 
  extensively 
  

   used 
  in 
  building. 
  

  

  The 
  upper 
  portion 
  of 
  the 
  group 
  is 
  what 
  was 
  originally 
  called 
  

   the 
  Corniferous 
  limestone, 
  from 
  its 
  containing 
  beds 
  and 
  nodules 
  

   of 
  hornstone 
  or 
  chert: 
  it 
  is 
  usually 
  from 
  30 
  to 
  50 
  feet 
  thick, 
  a 
  

   bluish 
  or 
  grayish 
  rock, 
  often 
  having 
  some 
  shale 
  interstratified 
  

   with 
  it. 
  Though 
  these 
  two 
  portions 
  of 
  the 
  Upper 
  Helderberg 
  

   limestone 
  are 
  in 
  most 
  places 
  very 
  distinct, 
  yet 
  in 
  others, 
  especially 
  

   in 
  the 
  west, 
  they 
  seem 
  to 
  run 
  together 
  or 
  blend 
  in 
  one 
  mass; 
  so 
  

   that 
  they 
  are 
  now 
  regarded 
  only 
  as 
  local 
  varieties 
  of 
  a 
  single 
  rock. 
  

  

  Upper 
  Devonian 
  Rocks 
  

   In 
  the 
  Upper 
  Helderberg 
  group, 
  we 
  have 
  the 
  last 
  or 
  highest 
  

   formation 
  of 
  limestone 
  of 
  any 
  considerable 
  extent 
  or 
  thickness 
  

   in 
  the 
  state. 
  All 
  the 
  southern 
  counties, 
  lying 
  above 
  or 
  south 
  of 
  

  

  