﻿GEOLOGIC 
  FORMATIONS 
  OF 
  NEW 
  YORK 
  16'i( 
  

  

  stones 
  seen 
  in 
  the 
  northern 
  counties 
  and 
  generally 
  around 
  the 
  

  

  edges 
  of 
  the 
  different 
  coal 
  fields. 
  In 
  southern 
  Pennsylvania 
  it 
  

  

  includes 
  limestones. 
  This 
  formation 
  has 
  not 
  been 
  recognized 
  in 
  

  

  New 
  York. 
  

  

  Pottsville 
  conglomerate 
  

  

  The 
  Mauch 
  Chunk 
  red 
  shale 
  is 
  covered 
  by 
  a 
  thick 
  series 
  of 
  

   strata, 
  known 
  as 
  the 
  Pottsville 
  conglomerate. 
  It 
  is 
  a 
  gray 
  and 
  

   whitish 
  conglomerate, 
  in 
  massive 
  beds 
  alternating 
  T^'ith 
  gray 
  

   sandstones, 
  and 
  consists 
  mainly 
  of 
  rolled 
  and 
  rounded 
  quartz 
  

   pebbles 
  cemented 
  with 
  ferruginous 
  sand 
  into 
  a 
  solid 
  mass. 
  Some 
  

   of 
  its 
  finer 
  or 
  more 
  sandy 
  layers 
  often 
  show 
  lamination 
  in 
  a 
  

   diagohal 
  or 
  slanting 
  direction. 
  It 
  is 
  1,700 
  feet 
  thick 
  at 
  its 
  maxi- 
  

   mum 
  and 
  often 
  contains 
  one 
  or 
  more 
  thin 
  seams 
  of 
  coal; 
  being 
  

   the 
  lowest 
  horizon 
  in 
  which 
  any 
  considerable 
  quantity 
  of 
  that 
  

   mineral 
  has 
  yet 
  been 
  found. 
  It 
  is 
  remarkably 
  massive 
  in 
  its 
  

   general 
  appearance, 
  the 
  ledges 
  often 
  separating 
  into 
  huge 
  blocks 
  

   with 
  wide 
  fissures 
  between, 
  which 
  have 
  been 
  fancifully 
  compared 
  

   to 
  ruined 
  cities. 
  Such 
  localities 
  are 
  to 
  be 
  seen 
  in 
  New 
  York 
  six 
  

   miles 
  south 
  of 
  Olean, 
  seven 
  miles 
  south 
  of 
  Ellicottville 
  and 
  near 
  

   Wellsville, 
  where 
  they 
  are 
  popularly 
  called 
  ' 
  rock-cities.' 
  This 
  

   is 
  locally 
  known 
  as 
  the 
  Olean 
  conglomerate. 
  

  

  The 
  ' 
  rock 
  cities 
  ' 
  lie 
  on 
  high 
  points 
  not 
  far 
  from 
  the 
  Pennsyl- 
  

   vania 
  line 
  and 
  are 
  simply 
  remnants 
  of 
  the 
  conglomerate 
  left 
  far 
  

   north 
  of 
  the 
  main 
  body 
  of 
  the 
  rock 
  by 
  the 
  wear 
  and 
  tear 
  of 
  the 
  

   elements, 
  which, 
  going 
  on 
  through 
  ages, 
  has 
  worn 
  away 
  this 
  mas- 
  

   sive 
  stratum 
  over 
  a 
  great 
  extent 
  of 
  country. 
  They 
  are 
  impressive 
  

   monuments 
  to 
  the 
  vastness 
  of 
  that 
  erosion, 
  which 
  has 
  left 
  them 
  in 
  

   this 
  isolated 
  position 
  and 
  which 
  will 
  in 
  the 
  course 
  of 
  future 
  

   centuries 
  demolish 
  them 
  entirely. 
  

  

  This 
  conglomerate 
  is 
  the 
  highest 
  and 
  latest 
  formed 
  of 
  all 
  Palae- 
  

   ozoic 
  rocks 
  known 
  within 
  the 
  limits 
  of 
  New 
  York. 
  In 
  Pennsyl- 
  

   vania 
  it 
  is 
  the 
  base 
  of 
  the 
  ' 
  Productive 
  Coal-measures,' 
  as 
  

   the 
  strata 
  containing 
  workable 
  layers 
  of 
  coal 
  are 
  called. 
  

   They 
  are 
  made 
  up 
  of 
  thick 
  beds 
  of 
  sandstones 
  and 
  black 
  

   shale, 
  with 
  which 
  the 
  coal 
  layers 
  are 
  interstratified. 
  The 
  coal 
  

   strata 
  are 
  of 
  all 
  thicknesses, 
  from 
  a 
  few 
  inches 
  up 
  to 
  20 
  or 
  even 
  

  

  