﻿178 
  T. 
  E. 
  Savage 
  — 
  Devonian 
  Formation 
  of 
  Illinois. 
  

  

  outcrop 
  also 
  occurs 
  just 
  below 
  the 
  dam 
  at 
  the 
  State 
  pond, 
  

   in 
  the 
  S.E.14, 
  sec. 
  14, 
  and 
  at 
  a 
  few 
  other 
  places 
  in 
  the 
  

   same 
  township. 
  This 
  shale 
  is 
  usually 
  considered 
  of 
  late 
  

   Devonian 
  age, 
  but 
  Ulrich 
  is 
  convinced 
  that 
  it 
  represents 
  

   early 
  Mississippian 
  rather 
  than 
  late 
  Devonian 
  time. 
  

   From 
  its 
  occurrence 
  near 
  Mountain 
  Glen 
  it 
  may 
  be 
  re- 
  

   ferred 
  to 
  as 
  the 
  "Mountain 
  Glen 
  shale.' 
  ' 
  

  

  Springville 
  Shale. 
  — 
  Unconformably 
  overlying 
  the 
  black 
  

   Mountain 
  Glen 
  shale 
  in 
  the 
  S.W. 
  1 
  ^, 
  sec. 
  11, 
  and 
  at 
  the 
  

   State 
  pond 
  in 
  sec. 
  14, 
  and 
  near 
  the 
  east 
  end 
  of 
  the 
  

   ridge 
  near 
  the 
  north 
  border 
  of 
  sec. 
  23 
  in 
  T.12S., 
  R.2W., 
  

   is 
  a 
  bed 
  of 
  greenish 
  shale 
  which 
  on 
  weathering 
  becomes 
  

   variegated 
  and 
  mottled 
  in 
  various 
  shades 
  of 
  brown 
  and 
  

   red. 
  This 
  formation 
  is 
  also 
  well 
  exposed 
  for 
  several 
  

   rods 
  along 
  the 
  creek 
  bank 
  in 
  the 
  S.E.14, 
  sec. 
  1, 
  T.13S., 
  

   R.2W., 
  and 
  in 
  many 
  other 
  places 
  south 
  of 
  Jonesboro^ 
  

   in 
  Union 
  County. 
  From 
  the 
  mottled 
  color 
  of 
  the 
  weath- 
  

   ered 
  portions 
  of 
  this 
  deposit 
  Worthen 
  referred 
  to 
  it 
  as 
  

   the 
  "Calico 
  shale. 
  " 
  In 
  some 
  places 
  in 
  the 
  vicinity 
  of 
  

   Elco 
  this 
  shale 
  has 
  locally 
  become 
  strongly 
  silicified, 
  

   and 
  the 
  deposit 
  has 
  been 
  worked 
  as 
  gannister, 
  and 
  used 
  

   by 
  the 
  Western 
  Firebrick 
  Company 
  in 
  the 
  manufacture 
  

   of 
  refractory 
  brick. 
  Worthen 
  considered 
  this 
  shale 
  the 
  

   youngest 
  of 
  the 
  Devonian 
  deposits 
  in 
  southern 
  Illinois. 
  

   It 
  is 
  unfossiliferous 
  in 
  most 
  of 
  the 
  exposures, 
  Leiorhyn- 
  

   chus 
  quadricostatum 
  being 
  the 
  only 
  species 
  found, 
  except 
  

   in 
  more 
  calcareous 
  lenses 
  in 
  the 
  lower 
  part 
  of 
  the 
  forma- 
  

   tion. 
  Such 
  lenses 
  in 
  the 
  S.W. 
  1 
  /^, 
  sec. 
  11, 
  and 
  at 
  the 
  

   State 
  pond, 
  in 
  T.12S. 
  H.2W., 
  furnished 
  Productella 
  con- 
  

   centrica, 
  Brachythyris 
  semiplicata, 
  B. 
  cf. 
  pecidiaris, 
  

   Amboccelia 
  unionensis, 
  and 
  cf. 
  Cardiopsis 
  radiata 
  which 
  

   ally 
  the 
  formation 
  with 
  the 
  early 
  Mississippian 
  (Rock- 
  

   ford) 
  limestone 
  or 
  southwestern 
  Indiana. 
  Good 
  expo- 
  

   sures 
  of 
  this 
  shale 
  occur 
  in 
  the 
  ridge 
  one 
  and 
  one 
  -half 
  

   miles 
  northwest 
  of 
  Jonesboro, 
  and 
  along 
  the 
  wagon 
  road 
  

   in 
  the 
  lower 
  part 
  of 
  the 
  hill 
  about 
  the 
  same 
  distance 
  

   south 
  of 
  Jonesboro, 
  and 
  in 
  the 
  hills 
  about 
  one 
  mile 
  west 
  

   of 
  this 
  town. 
  About 
  ^.ve 
  miles 
  south 
  of 
  Jonesboro 
  this 
  

   shale 
  is 
  also 
  well 
  exposed 
  in 
  the 
  bed 
  and 
  banks 
  of 
  a 
  

   creek 
  a 
  short 
  distance 
  northwest 
  of 
  the 
  village 
  of 
  Spring- 
  

   ville, 
  in 
  the 
  S.E.14, 
  sec. 
  13, 
  T.13S., 
  R.1W., 
  from 
  which 
  

   place 
  it 
  may 
  be 
  appropriately 
  called 
  the 
  Springville 
  

   shale. 
  

  

  