﻿44 
  ECONOMICAL 
  GEOLOGY. 
  

  

  In 
  the 
  vicinity 
  of 
  Brock's 
  ford, 
  two 
  miles 
  south 
  of 
  Streator, 
  a 
  

  

  limestone 
  occurs 
  near 
  the 
  top 
  of 
  the 
  hluff, 
  that 
  closely 
  resembles 
  

  

  the 
  limestone 
  south 
  of 
  Petersburg, 
  in 
  Menard 
  county, 
  which 
  there 
  

  

  lies 
  some 
  25 
  to 
  30 
  feet 
  above 
  coal 
  No. 
  7, 
  and 
  it 
  contains 
  a 
  similar 
  

  

  group 
  of 
  fossils. 
  In 
  addition 
  to 
  this, 
  the 
  shales 
  below 
  the 
  Streator 
  

  

  coal 
  contain 
  ironstone 
  concretions, 
  completely 
  filled 
  with 
  the 
  little 
  

  

  crustacean 
  figured, 
  and 
  described 
  in 
  a 
  preceding 
  volume 
  under 
  the 
  

  

  name 
  of 
  Leala 
  tricarinata, 
  which 
  is 
  regarded 
  as 
  a 
  characteristic 
  fossil 
  

  

  of 
  the 
  shales 
  under 
  coal 
  No. 
  7, 
  from 
  whence 
  it 
  has 
  been 
  obtained 
  

  

  at 
  several 
  localities 
  in 
  the 
  State. 
  The 
  following 
  section 
  shows 
  the 
  

  

  strata 
  to 
  be 
  seen 
  in 
  the 
  bluffs 
  of 
  the 
  Vermilion, 
  between 
  Brock's 
  

  

  ford 
  and 
  Streator. 
  

  

  . 
  In. 
  

  

  No. 
  1. 
  Light 
  gray 
  compact 
  limestone 
  4 
  

  

  No. 
  2. 
  Blue 
  sandy 
  shales 
  and 
  soft 
  sandstone, 
  with 
  concretions 
  of 
  s:indy 
  iron 
  ore 
  35 
  

  

  No. 
  3. 
  Bituminous 
  shale 
  I 
  

  

  No. 
  4. 
  Coal 
  No. 
  7 
  5 
  • 
  

  

  No.5. 
  Shale 
  with 
  discoidal 
  concretions 
  of 
  iron 
  ore 
  61 
  

  

  No. 
  «. 
  Fire-clay 
  

  

  No. 
  7. 
  Hard 
  con-retionary 
  sandstone 
  IS 
  to 
  IS 
  

  

  N'. 
  B. 
  Shaly 
  sandstone, 
  extending 
  below 
  the 
  river 
  level, 
  exposed 
  80 
  I 
  

  

  The 
  limestone 
  at 
  the 
  top 
  of 
  the 
  section 
  contains 
  several 
  sp. 
  

   of 
  small 
  Brachiopods, 
  the 
  most 
  common 
  being 
  Athyru 
  tubtilita, 
  

   Spirifer 
  linen 
  tux, 
  Terebrahda 
  bovideru, 
  and 
  a 
  small 
  NaHcoptu 
  

   Trackydomia, 
  which 
  were 
  mostly 
  in 
  the 
  form 
  of 
  casts, 
  the 
  pustulose 
  

   shell 
  being 
  removed. 
  

  

  The 
  hard 
  sandstone, 
  No. 
  7 
  of 
  the 
  section, 
  will 
  make 
  a 
  datable 
  

   stone 
  for 
  rough 
  walls 
  where 
  strength 
  is 
  the 
  main 
  requisr 
  

  

  Between 
  Streator 
  and 
  the 
  mouth 
  of 
  l'rairie 
  creek, 
  the 
  sandstone 
  

   under 
  the 
  Streator 
  coal 
  rises 
  so 
  as 
  to 
  form 
  with 
  the 
  sandy 
  shales 
  

   below, 
  a 
  perpendicular 
  cliff 
  about 
  forty 
  feel 
  in 
  height 
  Over 
  this 
  

   sandstone 
  ridge 
  the 
  coal 
  has 
  been 
  carried 
  away 
  by 
  the 
  denuding 
  

   agencies 
  of 
  the 
  Drift 
  period, 
  but 
  a 
  short 
  distance 
  away 
  from 
  the 
  

   river 
  it 
  comes 
  in 
  again 
  immediately 
  below 
  the 
  drift. 
  Near 
  the 
  

   mouth 
  of 
  the 
  creek 
  the 
  sandstone 
  becomes 
  thinner, 
  and 
  the 
  coal 
  

  

  appears 
  above 
  it 
  and 
  slopes 
  rapidly 
  down 
  to 
  the 
  river 
  level. 
  

  

  Several 
  borings 
  have 
  been 
  made 
  in 
  the 
  vicinity 
  of 
  Streator. 
  to 
  the 
  

   horizon 
  of 
  coal 
  No. 
  2, 
  but 
  1 
  was 
  unable 
  to 
  obtain 
  any 
  reliable 
  

   record 
  of 
  the 
  strata 
  passed 
  through. 
  I 
  WM 
  informed, 
  howevi 
  r. 
  that 
  

  

  the 
  distance 
  between 
  the 
  two 
  seams 
  was 
  about 
  80 
  feet. 
  The 
  quality 
  

  

  of 
  the 
  coal 
  afforded 
  by 
  No. 
  S 
  is 
  generally 
  superior 
  to 
  thai 
  of 
  any 
  

  

  of 
  the 
  higher 
  Beams, 
  but 
  it 
  seldom 
  exceeds 
  a 
  thickness 
  of 
  8 
  or 
  i 
  

  

  and 
  lying 
  deeper 
  below 
  the 
  surface, 
  and 
  consequently 
  reqoir- 
  

  

  