﻿112 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  consist 
  of 
  Georgian 
  rocks. 
  Likewise 
  at 
  Grant 
  hollow, 
  where 
  the 
  

   writer 
  found 
  the 
  Deep 
  Kill 
  graptolite 
  fauna 
  in 
  the 
  bottom 
  of 
  the 
  

   gorge, 
  the 
  tops 
  of 
  the 
  hills 
  on 
  both 
  sides 
  of 
  the 
  gorge 
  are 
  fossili- 
  

   ferous 
  Georgian. 
  The 
  latter 
  occurrence 
  is 
  of 
  great 
  interest 
  because 
  

   it 
  connects 
  the. 
  Ordovicic 
  shale 
  belt, 
  west 
  of 
  the 
  overthrust 
  line, 
  

   with 
  the 
  large 
  Mt 
  Rafinesque-Rice 
  Mountain 
  " 
  Outlier." 
  If 
  the 
  

   Georgian 
  rocks 
  overlie 
  the 
  Beekmantown 
  graptolite 
  shale 
  at 
  Grant 
  

   hollow, 
  it 
  can 
  be 
  inferred 
  that 
  this 
  outlier 
  is 
  really 
  a 
  " 
  Fenster," 
  or 
  

   a 
  portion 
  of 
  the 
  Ordovicic 
  rocks 
  underlying 
  here 
  the 
  Georgian 
  mass, 
  

   but 
  exposed 
  by 
  erosion. 
  

  

  There 
  is 
  considerable 
  and 
  quite 
  conclusive 
  evidence 
  that 
  the 
  

   thrust 
  plane 
  is 
  irregular 
  in 
  its 
  hade, 
  through 
  folding; 
  for 
  while 
  

   the 
  thrust 
  plane 
  is 
  very 
  slightly 
  inclined 
  at 
  Bald 
  mountain 
  and 
  

   the 
  Moses 
  kill, 
  it 
  is 
  steep 
  east 
  of 
  Willard 
  mountain, 
  and 
  in 
  the 
  

   neighborhood 
  of 
  Troy. 
  That 
  these 
  differences 
  are 
  due 
  to 
  folding 
  

   of 
  a 
  character 
  transversal 
  to 
  the 
  general, 
  northeast 
  strike 
  of 
  the 
  

   beds 
  is 
  indicated 
  by 
  the 
  fact 
  that 
  where 
  the 
  hade 
  is 
  steep, 
  the 
  

   Georgian 
  rocks 
  descend 
  deeper 
  than 
  where 
  it 
  is 
  flat, 
  as 
  in 
  the 
  val- 
  

   ley 
  of 
  the 
  Batten 
  kill, 
  these 
  regions 
  corresponding 
  to 
  depressions 
  

   or 
  synclines. 
  

  

  There 
  is 
  considerable 
  evidence 
  extant 
  of 
  folding 
  of 
  the 
  entire 
  

   region 
  long 
  after 
  the 
  Green 
  Mountain 
  revolution, 
  marking 
  the 
  

   Ordovicic-Siluric 
  boundary, 
  and 
  which 
  is 
  considered 
  responsible 
  

   for 
  the 
  principal 
  folding 
  and 
  overthrusting 
  of 
  this 
  region. 
  Such 
  

   later 
  folding 
  is 
  shown 
  by 
  the 
  folded 
  condition 
  of 
  the 
  Rensselaer 
  

   grit, 
  that 
  is 
  probably 
  of 
  Upper 
  Devonic 
  age, 
  and 
  the 
  remnants 
  

   of 
  the 
  folded 
  and 
  overthrust 
  Devonic 
  limestones 
  still 
  found 
  along 
  

   the 
  Hudson 
  river. 
  We 
  have 
  here 
  especially 
  in 
  mind 
  the 
  Kings- 
  

   ton 
  region, 
  the 
  folded 
  and 
  overthrust 
  structure 
  of 
  which 
  has 
  been 
  

   so 
  well 
  worked 
  out 
  by 
  Van 
  Ingen 
  and 
  Clark. 
  1 
  These 
  authors 
  

   have 
  shown 
  there 
  the 
  presence 
  of 
  a 
  practically 
  horizontal 
  over- 
  

   thrust 
  plane, 
  the 
  thrust 
  of 
  which 
  comes 
  from 
  the 
  east 
  and 
  which 
  

   is 
  possibly 
  a 
  manifestation 
  of 
  the 
  same 
  force 
  that 
  pushed 
  the 
  

   Georgian 
  rocks 
  over 
  the 
  Ordovicic 
  rocks 
  on 
  the 
  other 
  side 
  of 
  the 
  

   Hudson. 
  

  

  The 
  question 
  whether 
  the 
  overthrust 
  at 
  the 
  western 
  edge 
  of 
  

   the 
  Cambric 
  area 
  recognized 
  by 
  both 
  Doctor 
  Dale 
  and 
  the 
  writer, 
  

   reaches 
  so 
  far 
  back 
  east 
  that 
  the 
  large 
  Georgian 
  area 
  is 
  all 
  over- 
  

  

  1 
  Gilbert 
  van 
  Ingen 
  and 
  P. 
  Edwin 
  Clark. 
  Disturbed 
  Fossiliferous 
  Rocks 
  

   in 
  the 
  Vicinity 
  of 
  Rondout, 
  N. 
  Y. 
  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  69, 
  p. 
  1176. 
  1903. 
  

  

  