﻿T. 
  E. 
  Savage 
  — 
  Devonian 
  Formation 
  of 
  Illinois. 
  169 
  

  

  Art. 
  XII. 
  — 
  The 
  Devonian 
  Formations 
  of 
  Illinois; 
  by 
  

  

  T. 
  E. 
  Savage. 
  

  

  The 
  Devonian 
  rocks 
  in 
  Illinois 
  belong 
  to 
  two 
  distinct 
  

   provinces; 
  a 
  southern 
  or 
  Mexican 
  Gulf 
  province, 
  and 
  

   a 
  northern, 
  referred 
  to 
  by 
  Williams 
  as 
  the 
  Interior 
  

   Continental 
  province. 
  Of 
  these 
  provinces 
  the 
  former 
  

   contains 
  a 
  much 
  more 
  complete 
  sequence, 
  and 
  greater 
  

   thickness 
  of 
  Devonian 
  strata. 
  The 
  faunal 
  relations 
  of 
  

   this 
  southern 
  province 
  ally 
  it 
  much 
  more 
  closely 
  with 
  

   the 
  New 
  York 
  or 
  Eastern 
  Continental 
  province 
  which 
  

   was 
  connected 
  with 
  the 
  Atlantic 
  ocean, 
  than 
  to 
  the 
  Inte- 
  

   rior 
  Continental 
  province 
  which 
  had 
  a 
  connection 
  north- 
  

   ward 
  with 
  the 
  Arctic 
  ocean. 
  

  

  Devonian 
  Rocks 
  of 
  the 
  Southern 
  Province 
  in 
  Illinois. 
  

  

  The 
  detailed 
  field 
  study 
  of 
  the 
  geology 
  of 
  the 
  Jones- 
  

   boro 
  quadrangle 
  in 
  Union 
  County, 
  Illinois, 
  during 
  the 
  

   past 
  summer, 
  gave 
  the 
  writer 
  an 
  opportunity 
  to 
  restudy 
  

   the 
  area 
  of 
  Devonian 
  strata 
  in 
  southwest 
  Illinois. 
  The 
  

   Devonian 
  rocks 
  of 
  this 
  southern 
  province 
  do 
  not 
  extend 
  

   as 
  far 
  north 
  as 
  St. 
  Louis, 
  and 
  the 
  most 
  of 
  the 
  formations 
  

   are 
  not 
  certainly 
  known 
  in 
  the 
  state 
  north 
  of 
  Jackson 
  

   County, 
  although 
  several 
  of 
  them 
  are 
  known 
  in 
  Missouri 
  

   as 
  far 
  north 
  as 
  Ste. 
  Genevieve 
  County. 
  The 
  eastward 
  

   limits 
  of 
  this 
  basin 
  are 
  not 
  definitely 
  known, 
  exposures 
  

   of 
  the 
  rocks 
  being 
  mostly 
  restricted 
  to 
  a 
  belt 
  a 
  few 
  miles 
  

   wide 
  near 
  Mississippi 
  river. 
  A 
  small 
  area 
  of 
  Middle 
  

   Devonian 
  (Onondaga) 
  rocks 
  has 
  been 
  reported 
  by 
  Butts 
  1 
  

   in 
  Hardin 
  County 
  in 
  southeastern 
  Illinois, 
  and 
  rocks 
  of 
  

   corresponding 
  age 
  are 
  present 
  farther 
  east 
  in 
  Indiana 
  

   and 
  farther 
  south 
  in 
  western 
  Kentucky 
  and 
  Tennessee. 
  

  

  Thickness 
  of 
  Devonian 
  Strata. 
  — 
  The 
  total 
  aggregate 
  

   thickness 
  of 
  the 
  Devonian 
  rocks 
  of 
  the 
  southern 
  prov- 
  

   ince 
  in 
  southwest 
  Illinois 
  is 
  not 
  less 
  than 
  800 
  feet. 
  In 
  

   this 
  succession 
  of 
  strata, 
  all 
  of 
  the 
  series 
  or 
  larger 
  divi- 
  

   sions 
  of 
  the 
  Devonian 
  system 
  recognized 
  in 
  the 
  New 
  

   York 
  section 
  are 
  represented. 
  The 
  comparative 
  col- 
  

   umnar 
  sections 
  of 
  the 
  Devonian 
  formations 
  in 
  southwest 
  

   Illinois, 
  eastern 
  Missouri, 
  western 
  Tennessee, 
  and 
  

   eastern 
  Oklahoma, 
  and 
  their 
  equivalents 
  in 
  the 
  Xew 
  

   York 
  section, 
  are 
  shown 
  on 
  the 
  accompanying 
  plate, 
  2 
  

   given 
  in 
  two 
  parts 
  on 
  opposite 
  pages. 
  

  

  1 
  Butts, 
  Charles: 
  Illinois 
  Geol. 
  Survey, 
  Bull. 
  No. 
  35, 
  p. 
  75, 
  1917. 
  

  

  2 
  On 
  this 
  plate 
  the 
  thickness 
  of 
  the 
  Grand 
  Tower 
  limestone 
  (125 
  feet) 
  

   is 
  indicated 
  too 
  small; 
  and 
  the 
  thickness 
  of 
  the 
  Lingle 
  limestone 
  (90 
  feet) 
  

   is 
  indicated 
  too 
  great. 
  

  

  