﻿Ouachita 
  Mountain 
  System 
  in 
  Indian 
  Territory. 
  121 
  

  

  position 
  for 
  a 
  distance 
  of 
  twelve 
  miles. 
  From 
  north 
  to 
  south, 
  

   however, 
  the 
  following 
  distinct 
  sub-divisions 
  are 
  apparent. 
  

  

  Their 
  relation 
  however 
  is 
  indefinite, 
  owing 
  to 
  folds 
  and 
  

   faults 
  : 
  

  

  1. 
  Massive, 
  hard 
  blue 
  limestones. 
  Strata 
  of 
  20 
  feet 
  in 
  thick- 
  

  

  ness 
  alternating 
  with 
  thin 
  flaggy 
  layers. 
  Thickness 
  feet. 
  

   (interrupted 
  by 
  a 
  great 
  fault) 
  +280 
  

  

  2. 
  Massive 
  limestones, 
  but 
  in 
  thinner 
  and 
  more 
  flaggy 
  

  

  layers. 
  Cherty 
  ±100 
  

  

  3. 
  Thin 
  shaly 
  argillaceous 
  beds, 
  fossiliferous, 
  excessively 
  

  

  folded 
  and 
  crumpled. 
  Aggregate 
  thickness 
  includ- 
  

   ing 
  folds 
  _ 
  +360 
  

  

  4. 
  A 
  massive 
  bed 
  of 
  pure 
  white 
  loosely 
  cemented 
  sand- 
  

  

  stone, 
  similar 
  to 
  that 
  seen 
  above 
  the 
  Lower 
  Helder- 
  

  

  berg 
  near 
  Woodford. 
  _ 
  _..__ 
  95 
  

  

  5. 
  Thin 
  flags 
  and 
  shales, 
  mostly 
  concealed 
  but 
  seen 
  in 
  con- 
  

  

  tact 
  with 
  6 
  at 
  south 
  side 
  of 
  river 
  ._.. 
  ? 
  

  

  6. 
  A 
  massive, 
  yellow-blue 
  limestone; 
  finer 
  grained 
  than 
  

  

  No. 
  1; 
  rich 
  in 
  fossils 
  (Trilobites, 
  etc.) 
  South 
  bank 
  

  

  of 
  Washita 
  at 
  railroad 
  bridge 
  (Trenton) 
  +140 
  

  

  V. 
  Concealed 
  interval. 
  

  

  8. 
  Dark 
  blue 
  shales 
  of 
  great, 
  but 
  undetermined 
  thickness. 
  

  

  9. 
  Carboniferous 
  shales 
  and 
  sandstone, 
  Berwin 
  to 
  Overbrook. 
  

  

  Concerning 
  the 
  age 
  of 
  the 
  pre 
  Carboniferous 
  rocks 
  only 
  a 
  

   little 
  can 
  be 
  said, 
  but 
  sufficient 
  to 
  confirm 
  the 
  impression 
  that 
  

   they 
  include 
  Trenton 
  (No. 
  6), 
  Niagara? 
  (No 
  1), 
  Lower 
  Helder- 
  

   berg, 
  (No. 
  2). 
  Could 
  accurate 
  collections 
  be 
  made, 
  many 
  

   other 
  terranes 
  would 
  no 
  doubt 
  be 
  shown 
  to 
  exist. 
  The 
  basis 
  

   for 
  these 
  determinations 
  are 
  as 
  follows 
  Near 
  Woodford 
  post 
  

   office, 
  ten 
  miles 
  west 
  of 
  the 
  railroad, 
  I 
  collected 
  from 
  strata 
  

   which 
  are 
  continuous 
  with 
  and 
  apparently 
  the 
  same 
  as 
  No. 
  2 
  ? 
  

   the 
  following 
  fossils, 
  kindly 
  determined 
  by 
  Professor 
  H. 
  S. 
  

   Williams: 
  Spirifera 
  lamellosa, 
  Strojphomena 
  rugosa 
  {—rhom- 
  

   ooidalis), 
  Rhynchonella 
  nucleolata, 
  Lingula 
  f 
  rectilatra. 
  Con- 
  

   cerning 
  these 
  he 
  says 
  : 
  " 
  It 
  is 
  safe 
  to 
  say 
  the 
  horizon 
  is 
  Upper 
  

   Silurian 
  and 
  probably 
  equivalent 
  to 
  the 
  Lower 
  Helderberg 
  of 
  

   New 
  York. 
  It 
  is 
  above 
  the 
  Niagara, 
  and 
  this 
  is 
  an 
  interesting 
  

   feature." 
  Concerning 
  the 
  fossils 
  from 
  No. 
  6, 
  he 
  says 
  : 
  " 
  They 
  

   are 
  not 
  very 
  satisfactory 
  but 
  a 
  Trinucleus 
  concentricus 
  shows 
  

   No. 
  1092& 
  to 
  be 
  of 
  Lower 
  Silurian, 
  probably 
  Trenton 
  age." 
  

   A 
  fine 
  specimen 
  of 
  Lituites 
  oeckmani 
  Whitfield, 
  in 
  my 
  pos- 
  

   session, 
  I 
  have 
  cause 
  to 
  believe 
  came 
  from 
  this 
  same 
  locality, 
  

   although 
  I 
  had 
  previously 
  been 
  greatly 
  deceived 
  by 
  its 
  collec- 
  

   tor 
  as 
  to 
  its 
  locality 
  and 
  horizon. 
  

  

  It 
  is 
  not 
  my 
  desire 
  to 
  attempt 
  any 
  classification 
  of 
  these 
  pre- 
  

   Carboniferous 
  rocks, 
  but 
  I 
  believe 
  from 
  stratigraphic 
  evidence 
  

   that 
  the 
  shales 
  at 
  the 
  south 
  end 
  of 
  the 
  gap 
  may 
  prove 
  Devo- 
  

   nian. 
  Beneath 
  the 
  Trenton 
  rocks 
  there 
  are 
  exposed 
  still 
  older 
  

  

  