﻿88 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  skirting 
  the 
  eastern 
  foot 
  of 
  the 
  mountain. 
  This 
  belt 
  also 
  terminates 
  

   abruptly 
  against 
  the 
  Georgian 
  rocks 
  of 
  Louse 
  hill, 
  which 
  have 
  

   overridden 
  its 
  northern 
  continuation 
  in 
  the 
  over-thrust 
  movement. 
  

  

  The 
  boundaries 
  between 
  the 
  grit 
  zone, 
  shale 
  zone 
  and 
  white- 
  

   chert 
  bed 
  zone 
  are 
  not 
  sharply 
  delimited, 
  and 
  in 
  one 
  place 
  all 
  three 
  

   were 
  found 
  to 
  alternate 
  in 
  typical 
  beds 
  several 
  times 
  in 
  a 
  thickness 
  

   of 
  17 
  feet. 
  As 
  the 
  coarse 
  clastic 
  material 
  in 
  the 
  grit 
  indicates, 
  

   shallow 
  marine 
  conditions 
  prevailed 
  at 
  times 
  during 
  the 
  deposition 
  

   of 
  the 
  beds 
  and 
  the 
  supply 
  of 
  siliceous 
  and 
  argillaceous 
  mud 
  

   changed 
  at 
  times 
  very 
  rapidly. 
  

  

  The 
  true 
  stratigraphic 
  relation 
  of 
  the 
  shales, 
  white-weathering 
  

   beds 
  and 
  grit, 
  owing 
  to 
  the 
  intensely 
  folded 
  and 
  faulted 
  condition 
  

   of 
  the 
  region, 
  is 
  nowhere 
  shown 
  conclusively. 
  Dale 
  in 
  1899 
  (chart 
  

   facing 
  page 
  178) 
  gave 
  the 
  following 
  succession 
  in 
  descending 
  

   order: 
  Ig 
  Hudson 
  grits, 
  Hw 
  Hudson 
  white 
  beds, 
  G 
  Hudson 
  

   shales 
  ; 
  placing 
  the 
  grits 
  on 
  top 
  of 
  the 
  series. 
  In 
  1904 
  (page 
  37) 
  

   however, 
  he 
  published 
  the 
  following 
  table 
  showing 
  the 
  Hudson 
  

   formation 
  as 
  exposed 
  in 
  Rensselaer 
  county 
  and 
  the 
  northeastern 
  

   part 
  of 
  Columbia 
  county, 
  N. 
  Y. 
  : 
  

  

  ESTIMATED 
  

   DESCRIPTION 
  OF 
  STRATA 
  FAUNA 
  THICKNESS 
  IN 
  FEET 
  

  

  1 
  Black 
  shale 
  with 
  arenaceous 
  lime- 
  

  

  stone 
  (Ruedemann's 
  stations 
  24-26) 
  Dipl'ograptus 
  amplexi- 
  

  

  caulis 
  

  

  2 
  Black 
  and 
  gray 
  shale 
  with 
  inter- 
  

  

  bedded 
  grit 
  , 
  Normanskill 
  graptoltte 
  

  

  fauna 
  

  

  3 
  Similar 
  shale 
  with 
  limestone 
  and 
  

  

  limestone 
  conglomerate 
  Trenton 
  fauna 
  in 
  lime- 
  

   stone 
  and 
  cement 
  of 
  

   conglomerate 
  

  

  4 
  Black, 
  siliceous, 
  white-weathering, 
  

  

  cherty-looking 
  shale 
  1 
  

  

  5 
  Reddish, 
  purplish, 
  greenish 
  shale 
  with 
  

  

  small 
  quartzite 
  bands 
  

  

  Number 
  1 
  are 
  the 
  beds 
  here 
  described 
  as 
  the 
  Snake 
  Hill 
  forma- 
  

   tion, 
  and 
  no. 
  3 
  those 
  here 
  referred 
  to 
  the 
  Rysedorph 
  Hill 
  con- 
  

   glomerate, 
  and 
  placed 
  now, 
  on 
  faunal 
  evidence, 
  above 
  or 
  near 
  the 
  

   top 
  of 
  the 
  Normanskill 
  beds 
  ; 
  while 
  no. 
  5, 
  the 
  colored 
  shales, 
  are 
  

   not 
  exposed, 
  if 
  present, 
  on 
  the 
  Schuylerville 
  quadrangle. 
  It 
  will 
  

   be 
  seen 
  that 
  here 
  the 
  grits 
  are 
  also 
  placed 
  above 
  the 
  white 
  beds, 
  

   while 
  the 
  dark 
  shales 
  are 
  not 
  recognized 
  as 
  a 
  separate 
  subdivision. 
  

  

  1200-2500? 
  

  

  