﻿LIMESTONES 
  OF 
  NEW 
  YORK 
  AND 
  THEIR 
  ECONOMIC 
  VALUE 
  365 
  

  

  westward 
  to 
  Buffalo, 
  and 
  the 
  elevation 
  of 
  the 
  escarpment 
  de- 
  

   creases. 
  

  

  As 
  the 
  Helderberg. 
  limestones 
  are 
  of 
  considerable 
  thickness 
  in 
  

   New 
  York 
  state 
  it 
  may 
  be 
  well 
  to 
  mention 
  them 
  in 
  detail. 
  This 
  

   can 
  be 
  best 
  done 
  by 
  quoting 
  from 
  the 
  rejjort^of 
  Mr 
  N. 
  H. 
  Darton. 
  a 
  

  

  The 
  Helderberg 
  limestones 
  attain 
  their 
  greatest 
  development 
  

   in 
  eastern 
  New 
  York, 
  and 
  the 
  thickness 
  reported 
  by 
  Davis 
  of 
  

   about 
  300 
  feet 
  in 
  the 
  Catskill 
  region 
  is 
  the 
  maximum. 
  They 
  

   thin 
  gradually 
  southward 
  in 
  New 
  York, 
  but 
  expand 
  again 
  in 
  New 
  

   Jersey. 
  In 
  the 
  Helderberg 
  mountains 
  they 
  are 
  200 
  feet 
  and 
  at 
  

   Schoharie 
  not 
  over 
  240 
  feet. 
  Westward 
  from 
  Schoharie 
  the 
  

   thickness 
  decreases 
  very 
  gradually. 
  The 
  members 
  constituting 
  

   the 
  formation 
  in 
  its 
  typical 
  development 
  beginning 
  at 
  the 
  top 
  

   are, 
  a 
  pure 
  semi-crystalline, 
  massive, 
  very 
  fossiliferous 
  limestone, 
  

   a 
  thick 
  series 
  of 
  shaly 
  limestone, 
  and 
  the 
  basal 
  series, 
  thin 
  

   bedded 
  dark 
  limestones 
  of 
  the 
  Tentaculite 
  beds. 
  On 
  Catskill 
  

   creek 
  a 
  higher 
  member 
  of 
  impure 
  shaly 
  limestone 
  comes 
  in 
  above 
  

   the 
  pure, 
  massive 
  beds, 
  thickens 
  rapidly 
  and 
  continues 
  south- 
  

   ward 
  to 
  and 
  through 
  New 
  Jersey. 
  The 
  Helderberg 
  formation 
  

   preserves 
  its 
  typical 
  characters 
  with 
  some 
  local 
  variations 
  in 
  

   thickness 
  to 
  a 
  few 
  miles 
  weet 
  of 
  Cherry 
  Valley. 
  Then 
  the 
  upper 
  

   limestone 
  beds 
  thin 
  out 
  and 
  on 
  the 
  road 
  from 
  West 
  Winfield 
  to 
  

   Litchfield 
  in 
  the 
  southwestern 
  corner 
  of 
  Herkimer 
  county 
  the 
  

   Pentamerus 
  beds 
  lie 
  directly 
  under 
  the 
  Onondaga 
  limestone. 
  

   The 
  upper 
  members 
  of 
  the 
  Helderberg 
  limestones 
  which 
  come 
  in 
  

   again 
  westward 
  and 
  are 
  finely 
  exposed 
  at 
  Oriskany 
  Falls. 
  6 
  

   Here 
  120 
  feet 
  of 
  beds 
  are 
  exposed 
  in 
  and 
  about 
  the 
  quarries, 
  of 
  

   which 
  50 
  feet 
  are 
  quite 
  distinctly 
  of 
  the 
  Tentaculite 
  beds, 
  40 
  

   feet 
  of 
  gray 
  beds 
  in 
  greater 
  part 
  of 
  Pentamerus 
  limestone 
  age, 
  

   but 
  merging 
  into 
  the 
  character 
  of 
  the 
  lower 
  beds, 
  a 
  few 
  feet 
  of 
  

   beds 
  with 
  mixed 
  Pentamerus 
  and 
  shaly 
  limestone 
  fauna 
  and 
  at 
  

   the 
  top 
  25 
  feet 
  of 
  gray 
  subcrystalline 
  rock 
  containing 
  a 
  shaly 
  

   limestone 
  fauna. 
  25 
  miles 
  west 
  of 
  Perryville, 
  Madison 
  co. 
  

   this 
  condition 
  has 
  continued, 
  the 
  lower 
  members 
  expanding 
  ap- 
  

   parently 
  at 
  the 
  expense 
  of 
  the 
  Pentamerus 
  beds 
  and 
  the 
  upper 
  

   members 
  giving 
  place 
  to 
  Pentamerus 
  beds. 
  At 
  this 
  locality 
  the 
  

   Onondaga 
  limestone 
  was 
  seen 
  lying 
  on 
  a 
  few 
  feet 
  of 
  dark 
  gray 
  

   limestones 
  containing 
  Pentamerus, 
  with 
  a 
  thin 
  local 
  intervening 
  

   layer 
  of 
  Oriskany 
  at 
  one 
  point, 
  which 
  gave 
  place 
  to 
  a 
  great 
  mass 
  

   of 
  thin 
  bedded 
  gray 
  limestone 
  below. 
  

  

  a 
  Report 
  on 
  the 
  relations 
  of 
  the 
  Helderberg 
  limestones 
  and 
  associated 
  formations 
  in 
  

   eastern 
  New 
  York. 
  13th 
  an. 
  rep't 
  N. 
  Y. 
  state 
  geol. 
  1893, 
  p. 
  204. 
  

  

  o 
  See 
  also 
  S. 
  G. 
  Williams. 
  The 
  westward 
  extension 
  of 
  rocks 
  of 
  the 
  Lower 
  Held- 
  

   erberg 
  age 
  in 
  New 
  York, 
  Amer. 
  jour. 
  sci. 
  3d 
  series, 
  31:139-45; 
  Abstract 
  Am. 
  ass, 
  ady. 
  

   sci. 
  Proc. 
  34:235, 
  236; 
  Amer. 
  nat. 
  1886, 
  20:373. 
  

  

  