﻿FIFTH 
  REPORT 
  OF 
  THE 
  DIRECTOR 
  I908 
  3 
  1 
  

  

  and 
  Devonic 
  time, 
  no 
  rocks 
  of 
  tliis 
  age 
  being 
  determinable. 
  Profes- 
  

   sor 
  Emerson 
  regards 
  all 
  the 
  rocks 
  above 
  these 
  mentioned 
  as 
  Car- 
  

   bonic 
  coextensive 
  with 
  the 
  Worcester 
  and 
  Mansfield 
  coals. 
  

  

  These 
  conclusions 
  give 
  evidence 
  enough 
  of 
  an 
  old 
  land 
  barrier 
  

   bounding 
  a 
  trough 
  of 
  Devonic 
  waters 
  in 
  which 
  the 
  metamoiiphosed 
  

   beds 
  of 
  Bernardston 
  at 
  least 
  were 
  deposited. 
  The 
  rest 
  may 
  have 
  

   been 
  removed 
  by 
  erosion, 
  but 
  in 
  eastern 
  New 
  York 
  between 
  the 
  

   Hudson 
  and 
  the 
  IMassachusetts 
  line 
  and 
  in 
  the 
  direction 
  of 
  the 
  

   Devonic 
  rocks 
  of 
  Bernardston 
  lies 
  an 
  extensive 
  sheet 
  of 
  coarse 
  

   clastic 
  material 
  known 
  as 
  the 
  Rensselaer 
  grit 
  which 
  at 
  this 
  point 
  

   requires 
  brief 
  attention. 
  

  

  Rensselaer 
  grit. 
  Rensselaer 
  and 
  Columbia 
  counties, 
  New 
  York, 
  

   lying 
  east 
  of 
  the 
  Hudson 
  river 
  and 
  in 
  the 
  general 
  direction 
  of 
  

   continuity 
  between 
  the 
  Helderberg-Catskill 
  escarpment 
  and 
  the 
  

   Bernardston 
  Devonic 
  outcrops 
  of 
  the 
  Connecticut 
  valley, 
  are 
  ex- 
  

   tensively 
  mantled 
  by 
  heavy 
  arenaceous 
  deposits 
  lying 
  unconform- 
  

   ably 
  on 
  the 
  unfolded 
  Cambric 
  and 
  Lower 
  Siluric 
  strata 
  beneath. 
  

   The 
  character 
  and 
  distribution 
  of 
  this 
  rock 
  was 
  clearly 
  outlined 
  by 
  

   Lieutenant 
  Mather 
  in 
  his 
  report 
  on 
  the 
  first 
  geological 
  district 
  

   {1843) 
  ^^^^ 
  ^t 
  ^^'^^ 
  regarded 
  by 
  him 
  as 
  equivalent 
  in 
  age 
  with 
  the 
  

   Shawangunk 
  grit 
  of 
  Ulster 
  and 
  Orange 
  counties 
  on 
  the 
  west 
  of 
  the 
  

   river. 
  

  

  The 
  early 
  geologists 
  held 
  the 
  Shawangunk 
  grit 
  to 
  be 
  an 
  eastern 
  

   representation 
  of 
  tlie 
  Oneida 
  grit 
  of 
  central 
  New 
  York 
  and 
  this 
  

   conception 
  has 
  been 
  quite 
  generally 
  promulgated. 
  Mr 
  T. 
  Nelson 
  

   Dale 
  has 
  been 
  one 
  of 
  the 
  latest 
  investigators 
  of 
  this 
  reg'ion 
  and 
  has 
  

   acquired 
  an 
  intimate 
  knowledge 
  of 
  the 
  stratigraphic 
  relations 
  of 
  

   this 
  terrane 
  to 
  the 
  unconformable 
  rocks 
  beneath 
  and 
  we 
  owe 
  to 
  

   him 
  the 
  conclusion 
  that 
  the 
  up 
  folding 
  of 
  the 
  lower 
  and 
  upper 
  

   lerranes 
  pertains 
  to 
  different 
  dates, 
  the 
  former 
  to 
  the 
  Taconic 
  and 
  

   the 
  latter 
  to 
  the 
  Postdevonic 
  or 
  Carbonic 
  movement 
  which 
  also 
  

   produced 
  the 
  more 
  southerly 
  synclines 
  now 
  represented 
  by 
  Becraft 
  

   mountain, 
  Columbia 
  county. 
  Mr 
  Dale 
  has 
  correlated 
  the 
  Rens- 
  

   selaer 
  grit 
  with 
  the 
  entire 
  Oneida-^NIedina 
  sedimentation 
  of 
  eastern 
  

   New 
  York. 
  In 
  recent 
  investigations 
  carried 
  on 
  by 
  C. 
  A. 
  Hart- 
  

   nagel 
  [see 
  AIus. 
  Bui. 
  107. 
  1907. 
  p. 
  51 
  1 
  it 
  is 
  shown 
  with 
  approxi- 
  

   mate 
  conclusiveness 
  that 
  in 
  the 
  typical 
  sections 
  of 
  central 
  New 
  

   York 
  the 
  Oneida 
  conglomerate 
  is 
  not 
  a 
  formational 
  unit 
  but 
  

   actually 
  lies 
  within 
  the 
  Medina 
  sandstones 
  ; 
  that, 
  further, 
  the 
  Shaw- 
  

   angunk 
  grit, 
  on 
  stratigraphic 
  evidence 
  alone, 
  is 
  of 
  an 
  age 
  much 
  

   later 
  than 
  the 
  Medina 
  formation 
  and 
  being 
  overlain 
  by 
  rocks 
  of 
  

   Postsalina 
  age 
  is 
  presumably 
  the 
  eastern 
  representation 
  of 
  Salina 
  

  

  