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  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  The 
  area 
  in 
  which 
  the 
  Niagara 
  limestone 
  is 
  found 
  is 
  more 
  re- 
  

   stricted 
  than 
  that 
  of 
  most 
  of 
  the 
  other 
  limestone 
  formations 
  of 
  

   the 
  state. 
  The 
  upper 
  member 
  of 
  this 
  formation 
  is 
  known 
  as 
  the 
  

   Guelph 
  limestone 
  but 
  is 
  not 
  coextensive 
  with 
  the 
  lower 
  member. 
  

   It 
  forms 
  a 
  lenticular 
  bed 
  about 
  20 
  miles 
  long 
  and 
  extends 
  from 
  

   Eochester 
  westward. 
  In 
  the 
  vicinity 
  of 
  Eochester 
  quarries 
  have 
  

   been 
  opened 
  in 
  it 
  at 
  Sew 
  Brighton 
  and 
  Gates. 
  As 
  exposed 
  in 
  

   these 
  quarries 
  it 
  is 
  a 
  grayish 
  brown, 
  finely 
  crystalline 
  limestone 
  

   containing 
  numbers 
  of 
  small 
  cavities. 
  The 
  peculiar 
  feature 
  of 
  

   this 
  rock 
  is 
  that 
  it 
  contains 
  a 
  large 
  amount 
  of 
  magnesia 
  and 
  a 
  

   very 
  low 
  silica 
  percentage, 
  making 
  it 
  very 
  adaptable 
  for 
  use 
  in 
  

   the 
  lining 
  of 
  bessemer 
  converters. 
  

  

  Helderberg 
  limestones. 
  These 
  include 
  several 
  distinct 
  members 
  

   which 
  are 
  known 
  as 
  the 
  Tentaculite, 
  water 
  lime, 
  Pentamerus, 
  

   Oatskill 
  shaly, 
  Becraft 
  and 
  upper 
  shaly 
  limestones. 
  

  

  The 
  formation 
  is 
  a 
  widely 
  distributed 
  one 
  within 
  the 
  state 
  and 
  

   of 
  considerable 
  economic 
  importance, 
  containing 
  the 
  hydraulic 
  

   limestones 
  which 
  are 
  so 
  extensively 
  developed 
  at 
  Eosendale 
  near 
  

   Kingston 
  in 
  Ulster 
  co. 
  and 
  through 
  the 
  western 
  part 
  of 
  the 
  state. 
  

  

  Its 
  members 
  enter 
  the 
  state 
  at 
  the 
  southeastern 
  corner 
  just 
  east 
  

   of 
  Port 
  Jervis, 
  New 
  York. 
  They 
  then 
  follow 
  up 
  the 
  southeastern 
  

   side 
  of 
  the 
  valley 
  of 
  Neversink 
  river, 
  Basherkill, 
  and 
  Eondout 
  

   creek. 
  Throughout 
  this 
  whole 
  distance 
  the 
  limestone 
  rests 
  on 
  the 
  

   Shawangunk 
  grit 
  which 
  forms 
  the 
  crest 
  of 
  the 
  Shawangunk 
  moun- 
  

   tain. 
  From 
  Kingston 
  the 
  same 
  formation 
  extends 
  northward 
  past 
  

   Catskill 
  to 
  New 
  Baltimore 
  where 
  it 
  then 
  swings 
  to 
  the 
  north- 
  

   west, 
  extending 
  as 
  far 
  as 
  New 
  Salem 
  in 
  Albany 
  co. 
  At 
  this 
  

   point 
  it 
  becomes 
  very 
  narrow 
  but 
  appears 
  again 
  as 
  a 
  some- 
  

   what 
  broad 
  belt 
  just 
  west 
  of 
  Meadowdale 
  in 
  the 
  same 
  county 
  

   and 
  then 
  extends 
  westward 
  as 
  far 
  as 
  Central 
  Bridge 
  in 
  

   Schenectady 
  co. 
  and 
  from 
  there 
  in 
  a 
  slightly 
  northwest 
  direc- 
  

   tion 
  past 
  Sharon 
  Springs, 
  Dennisons 
  Corners, 
  Oneida, 
  Syra- 
  

   cuse, 
  and 
  westward 
  to 
  Niagara 
  Falls. 
  Up 
  to 
  Dennisons 
  Corners 
  

   the 
  formation 
  though 
  of 
  considerable 
  thickness 
  does 
  not 
  cover 
  a 
  

   very 
  broad 
  belt 
  owing 
  to 
  the 
  perpendicular 
  escarpment 
  which 
  it 
  

   forms, 
  but 
  its 
  thickness 
  remains 
  about 
  the 
  same 
  from 
  Svracuse 
  

  

  