﻿368 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  the 
  upper 
  10 
  feet 
  consisting 
  of 
  impure 
  and 
  sandy 
  or 
  shaly 
  layers. 
  

   There 
  are 
  as 
  Davis 
  suggests 
  many 
  local 
  slips 
  in 
  this 
  section 
  and 
  

   my 
  estimate 
  of 
  the 
  thickness 
  of 
  the 
  purer 
  limestone 
  would 
  be 
  

   about 
  60 
  feet. 
  

  

  " 
  In 
  the 
  Rondout 
  region 
  the 
  Becraft 
  limestone 
  is 
  40 
  feet 
  thick 
  

   and 
  the 
  upper 
  shaly 
  beds 
  100 
  to 
  150 
  feet 
  thick. 
  In 
  the 
  ridge 
  just 
  

   east 
  of 
  Whiteport 
  there 
  are 
  30 
  feet 
  of 
  Becraft 
  limestone." 
  About 
  

   Rosendale 
  and 
  southward 
  no 
  exposures 
  have 
  been 
  noted 
  by 
  

   Darton. 
  " 
  Underlying 
  the 
  Becraft 
  limestone 
  throughout 
  are 
  the 
  

   lower 
  shaly 
  beds 
  consisting 
  of 
  thin-bedded, 
  impure, 
  highly 
  fos- 
  

   siliferous 
  limestone 
  with 
  some 
  shale 
  beds." 
  At 
  some 
  localities 
  

   though, 
  as 
  for 
  instance 
  westward 
  on 
  the 
  Foxkill 
  above 
  Gallup- 
  

   ville, 
  it 
  is 
  in 
  greater 
  part 
  a 
  massive, 
  relatively 
  pure 
  limestone. 
  

   In 
  Greene 
  and 
  Ulster 
  counties 
  it 
  has 
  the 
  character 
  of 
  the 
  upper 
  

   shaly 
  beds, 
  with 
  a 
  more 
  or 
  less 
  slaty 
  cleavage 
  and 
  outcropping 
  

   in 
  ragged 
  ledges, 
  in 
  some 
  cases 
  closely 
  resembling 
  the 
  lighter 
  

   colored 
  outcrops 
  of 
  the 
  Esopus 
  state. 
  Its 
  thickness 
  from 
  Scho- 
  

   harie 
  eastward 
  is 
  about 
  80 
  feet, 
  and 
  there 
  and 
  elsewhere 
  in 
  the 
  

   great 
  Helderberg 
  escarpment 
  it 
  constitutes 
  a 
  steep 
  slope 
  between 
  

   the 
  Scutella 
  and 
  Oriskany 
  shelf 
  above 
  the 
  Pentamerus 
  escarp- 
  

   ment 
  below. 
  Its 
  thickness 
  apparently 
  decreases 
  somewhat 
  in 
  the 
  

   Kingston-Rosendale 
  region 
  but 
  it 
  retains 
  its 
  characteristics. 
  

  

  The 
  Pentamerus 
  or 
  lower 
  Pentamerus 
  are 
  the 
  most 
  conspicu- 
  

   ous 
  members 
  of 
  the 
  lower 
  Helderberg 
  formation. 
  They 
  give 
  rise 
  

   to 
  the 
  great 
  escarpment 
  which 
  marks 
  the 
  eastern 
  edge 
  of 
  the 
  

   Helderberg 
  formation 
  as 
  it 
  passes 
  along 
  through 
  central 
  New 
  

   York. 
  

  

  The 
  beds 
  are 
  mostly 
  hard, 
  massive 
  bedded 
  and 
  vertical 
  

   jointed 
  limestones. 
  The 
  rock 
  is 
  generally 
  bluish 
  gray 
  in 
  color 
  

   but 
  weathering 
  imparts 
  a 
  lighter 
  tint 
  to 
  the 
  surface. 
  Partings 
  

   of 
  slate 
  occur 
  occasionally 
  as 
  well 
  as 
  lenses 
  of 
  chert, 
  specially 
  in 
  

   the 
  east 
  and 
  south. 
  

  

  The 
  Pentamerus 
  limestone 
  is 
  a 
  quite 
  uniform 
  member 
  and 
  its 
  

   thickness 
  does 
  not 
  vary 
  greatly. 
  "At 
  Schoharie 
  its 
  thickness 
  is 
  

   between 
  60 
  and 
  70 
  feet, 
  in 
  the 
  Helderbergs 
  it 
  is 
  the 
  same 
  and 
  a 
  

   trifle 
  more 
  about 
  Catskill 
  (80 
  feet 
  according 
  to 
  Davis), 
  50 
  feet 
  at 
  

  

  