﻿Williams 
  — 
  Devonian 
  Interval 
  in 
  northern 
  ArJcansas. 
  149 
  

  

  allowed 
  to 
  limit 
  the 
  range 
  of 
  the 
  fauna 
  it 
  contains. 
  The 
  fauna, 
  

   which 
  is 
  well 
  exhibited 
  as 
  soon 
  as 
  the 
  green 
  shales 
  are 
  in 
  force, 
  

   is 
  always 
  of 
  Carboniferous 
  type 
  ; 
  and 
  in 
  one 
  case, 
  we 
  have 
  a 
  

   black 
  shale 
  also 
  containing 
  the 
  same 
  fauna, 
  which 
  I 
  refer 
  to 
  

   the 
  black 
  shale 
  of 
  the 
  War 
  Eagle 
  Creek 
  section 
  (12Y9 
  Al), 
  thus 
  

   clearly 
  indicating 
  the 
  stratigraphical 
  continuity 
  of 
  the 
  green 
  

   and 
  black 
  shales 
  of 
  the 
  general 
  region. 
  

  

  The 
  fauna 
  associated 
  generally 
  with 
  the 
  pure 
  black 
  shale 
  

   sediments 
  in 
  Arkansas, 
  and 
  in 
  other 
  regions 
  in 
  the 
  south, 
  is 
  

   restricted 
  to 
  very 
  few 
  species, 
  of 
  which 
  the 
  Lingula 
  is 
  the 
  

   most 
  frequent 
  often 
  associated 
  with 
  Conodont 
  teeth. 
  This 
  is 
  

   also 
  characteristic 
  of 
  the 
  Genesee 
  black 
  shale 
  of 
  Kew 
  York. 
  

   My 
  conclusion 
  from 
  the 
  study 
  of 
  the 
  whole 
  problem 
  is, 
  how- 
  

   ever, 
  that 
  the 
  fauna 
  of 
  the 
  Genesee 
  black 
  shale, 
  which 
  has 
  a 
  

   definite 
  limited 
  position 
  in 
  the 
  New 
  York 
  section, 
  is 
  a 
  fauna 
  

   of 
  wide 
  geological 
  range, 
  and 
  is 
  characteristic 
  of 
  the 
  black 
  

   shale 
  conditions 
  of 
  sedimentation 
  rather 
  than 
  of 
  the 
  particular 
  

   limited 
  horizon 
  represented 
  by 
  the 
  Genesee 
  formation. 
  The 
  

   fauna 
  in 
  these 
  fine 
  shales 
  in 
  Arkansas, 
  terminating 
  and 
  follow- 
  

   ing 
  the 
  black 
  shales, 
  is 
  unmistakably 
  much 
  higher 
  than 
  the 
  

   Genesee 
  black 
  shale 
  of 
  New 
  York. 
  Faunally, 
  it 
  is 
  the 
  cor- 
  

   relative 
  of 
  the 
  Louisiana 
  or 
  lithographic 
  limestone, 
  and 
  is 
  thus 
  

   as 
  late 
  as 
  the 
  Kinderhook 
  stage 
  of 
  the 
  Eocarboniferous. 
  

  

  There 
  can 
  be 
  no 
  doubt 
  regarding 
  the 
  Carboniferous 
  age 
  of 
  

   the 
  faunas 
  of 
  the 
  typical 
  Louisiana 
  limestone. 
  Its 
  fauna 
  is 
  

   characteristically 
  Kinderhook, 
  Waverly, 
  Chouteau, 
  and 
  it 
  is 
  

   not 
  paleontologically 
  correct 
  to 
  refer 
  the 
  Louisiana 
  and 
  Hanni- 
  

   bal 
  (or 
  those 
  Arkansas 
  formations 
  which 
  belong 
  to 
  the 
  same 
  

   epoch) 
  to 
  the 
  Devonian 
  (as 
  Mr. 
  Keyes 
  has 
  done 
  in 
  the 
  Biennial 
  

   Report 
  of 
  the 
  Stale 
  Geologist 
  of 
  Missouri 
  for 
  1897, 
  page 
  59). 
  

   The 
  fauna 
  of 
  the 
  shales 
  terminating 
  the 
  interval 
  deposits 
  in 
  

   Arkansas, 
  is 
  evidently 
  the 
  same 
  as 
  that 
  seen 
  in 
  a 
  similar 
  posi- 
  

   tion 
  in 
  the 
  Louisiana 
  section 
  in 
  Missouri, 
  and 
  thus 
  belongs 
  to 
  

   the 
  base 
  of 
  the 
  Chouteau 
  or 
  Kinderhook 
  group. 
  

  

  The 
  age 
  of 
  the 
  Sylamore 
  sandstone 
  and 
  associated 
  dejoosits. 
  — 
  

   From 
  a 
  study 
  of 
  all 
  the 
  evidence 
  visible, 
  both 
  stratigraphical 
  

   and 
  paleontological, 
  I 
  have 
  reached 
  the 
  following 
  conclusions 
  

   regarding 
  the 
  probable 
  age 
  of 
  the 
  formation 
  of 
  this 
  interval- 
  

   material. 
  The 
  distinct 
  fossiliferous 
  deposit 
  of 
  black 
  shale 
  seen 
  

   in 
  Cagen 
  Creek 
  section 
  (1216 
  A) 
  cannot 
  be 
  distinguished 
  pale- 
  

   ontologically 
  from 
  the 
  " 
  Black 
  shales 
  " 
  of 
  the 
  Tennessee, 
  Ken- 
  

   tucky 
  and 
  Indiana 
  sections. 
  The 
  St. 
  Joe 
  sections 
  indicate 
  

   distinctly 
  that 
  the 
  green 
  shale 
  and 
  the 
  Sylamore 
  sandstone 
  were 
  

   formed 
  at 
  the 
  same 
  geological 
  time, 
  i. 
  e., 
  consecutively 
  ; 
  and 
  

   that 
  the 
  Carboniferous 
  deposit, 
  following, 
  was 
  formed 
  after 
  the 
  

   Sylamore 
  sandstone 
  was 
  laid 
  down, 
  hence 
  that 
  the 
  sandstone 
  

   with 
  its 
  nodules, 
  and 
  the 
  green 
  mud-shale 
  associated 
  with 
  it, 
  

  

  