﻿66 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  PALEOZOIC 
  ROCKS 
  OF 
  THE 
  EASTERN 
  TROUGH 
  

  

  BY 
  R. 
  RUEDEMANN 
  

  

  All 
  the 
  sedimentary 
  formations 
  of 
  the 
  eastern 
  trough 
  in 
  the 
  

   Saratoga 
  and 
  Schuylerville 
  quadrangles 
  belong 
  to 
  the 
  Cambric 
  and 
  

   Ordovicic 
  (Lower 
  Siluric) 
  systems. 
  The 
  following 
  stratigraphic 
  

   units 
  have 
  been 
  distinguished 
  : 
  

  

  Table 
  of 
  formations 
  exposed 
  

  

  f 
  9 
  Snake 
  Hill 
  shale 
  

   Trenton 
  \ 
  8 
  Upper 
  Normanskill 
  shale 
  with 
  

  

  Rysedorph 
  Hill 
  conglomerate 
  

  

  Chazy 
  < 
  7 
  Normanskill 
  shale 
  s. 
  str. 
  

  

  Ordovicic 
  < 
  

  

  { 
  6 
  Bald 
  Mountain 
  limestone 
  

   Beekmantown 
  <j 
  5 
  Deep 
  Kill 
  shale 
  (possibly 
  present) 
  

   I 
  4 
  Schaghticoke 
  shale 
  

  

  I 
  Georgian 
  f 
  3 
  Schodack 
  shales 
  and 
  limestones 
  

  

  Cambric 
  ^ 
  or 
  i 
  2 
  Eddy 
  Hill 
  grit 
  

  

  [Taconic 
  I 
  1 
  Bomoseen 
  grit 
  

  

  The 
  Cambric 
  system 
  is 
  represented 
  only 
  by 
  its 
  lowest 
  group, 
  the 
  

   Georgian. 
  The 
  Georgian 
  rocks 
  are 
  found 
  only 
  along 
  the 
  eastern 
  

   edge 
  of 
  the 
  Schuylerville 
  sheet, 
  whence 
  they 
  extend 
  eastward 
  over 
  

   the 
  Greenwich 
  and 
  Rensselaer 
  plateaus. 
  The 
  discovery 
  and 
  

   demonstration 
  of 
  the 
  presence 
  of 
  Lower 
  Cambric 
  rocks, 
  now 
  

   known 
  as 
  Georgian, 
  may 
  be 
  said 
  to 
  have 
  taken 
  place 
  right 
  at 
  this 
  

   eastern 
  edge, 
  for 
  it 
  was 
  from 
  the 
  neighborhood 
  of 
  Bald 
  moun- 
  

   tain 
  that 
  Dr 
  Ebenezer 
  Emmons 
  obtained 
  the 
  fossils 
  E 
  1 
  1 
  i 
  p 
  t 
  o 
  - 
  

   cephalus 
  asaphoides 
  and 
  At 
  ops 
  trilineatus 
  which 
  

   demonstrated, 
  in 
  that 
  well-known 
  controversy 
  on 
  the 
  Cambric 
  

   system 
  in 
  America 
  (Emmons's 
  Taconic), 
  the 
  presence 
  of 
  rocks 
  

   as 
  old 
  as 
  the 
  Primordial 
  stage 
  of 
  Barrande 
  in 
  the 
  slate 
  belt 
  of 
  

   eastern 
  New 
  York. 
  Through 
  the 
  investigations 
  of 
  Ford, 
  and 
  

   especially 
  those 
  of 
  Walcott 
  and 
  Dale, 
  the 
  faunas 
  and 
  rock 
  types 
  

   of 
  the 
  Georgian 
  have 
  become 
  well 
  known. 
  Walcott 
  1 
  first 
  clearly 
  

   separated 
  the 
  Georgian 
  and 
  Ordovician 
  terranes, 
  and 
  Dale 
  2 
  

  

  1 
  The 
  Taconic 
  System 
  of 
  Emmons. 
  Amer. 
  Jour. 
  Science, 
  1888, 
  35 
  :22Q, 
  307. 
  

  

  2 
  Dale, 
  T. 
  Nelson. 
  New 
  York- 
  Vermont 
  Slate 
  Belt. 
  U. 
  S. 
  Geol. 
  Surv. 
  

   19th 
  Ann. 
  Rep't, 
  1893, 
  p. 
  153. 
  

  

  