﻿LA 
  SALLE 
  COUNTY. 
  47 
  

  

  Feet. 
  

  

  No. 
  7. 
  Nodular 
  shale, 
  or 
  shaly 
  limestone 
  6 
  

  

  No. 
  8. 
  Upper 
  main 
  limestone 
  12 
  

  

  No. 
  9. 
  Green 
  shale 
  2 
  

  

  No. 
  10. 
  Lower 
  limestone 
  10 
  to 
  12 
  

  

  These 
  are 
  the 
  highest 
  Coal 
  Measure 
  strata 
  outcropping 
  in 
  the 
  

   county, 
  and 
  they 
  have 
  been 
  referred 
  by 
  some 
  observers 
  to 
  the 
  

   Permian 
  age, 
  but 
  I 
  was 
  unable 
  to 
  find 
  any 
  satisfactory 
  evidence 
  of 
  

   unconformability 
  between 
  them 
  and 
  the 
  limestone 
  No. 
  3, 
  on 
  which 
  

   they 
  rest, 
  and 
  the 
  fossils, 
  so 
  far 
  as 
  they 
  have 
  been 
  determined, 
  are 
  

   of 
  well-known 
  Coal 
  Measure 
  forms. 
  

  

  The 
  most 
  common 
  fossils 
  in 
  the 
  calcareous 
  shales 
  and 
  impure 
  

   limestones 
  of 
  this 
  horizon 
  were 
  the 
  following 
  species 
  : 
  Orthis 
  Pecosii, 
  

   Chonetes 
  Flemingi, 
  Productus 
  La 
  Sallensis, 
  Hemipronites 
  crassa, 
  Athy- 
  

   ris 
  subtilita, 
  all 
  of 
  which 
  are 
  characteristic 
  Coal 
  Measure 
  forms. 
  

   On 
  the 
  south 
  side 
  of 
  the 
  Illinois, 
  these 
  .beds 
  make 
  their 
  appearance 
  

   in 
  the 
  cat 
  of 
  the 
  Illinois 
  Central 
  railroad 
  from 
  the 
  river 
  bluff 
  to 
  a 
  

   point 
  half 
  a 
  mile 
  or 
  more 
  beyond 
  Oglesby, 
  where 
  the 
  railroad 
  grade 
  

   finally 
  ascends 
  entirely 
  above 
  them 
  and 
  onto 
  the 
  overlying 
  drift 
  

   deposits. 
  

  

  The 
  beds 
  immediately 
  below 
  the 
  main 
  limestones 
  are 
  well 
  ex- 
  

   posed 
  in 
  the 
  bluffs 
  between 
  La 
  Salle 
  and 
  Peru, 
  and 
  there 
  is 
  a 
  de- 
  

   cided 
  increase 
  in 
  the 
  thickness 
  of 
  the 
  shales 
  as 
  we 
  recede 
  from 
  the 
  

   axis 
  of 
  disturbance, 
  already 
  mentioned 
  on 
  a 
  preceding 
  page. 
  On 
  the 
  

   Little 
  Vermilion 
  where 
  it 
  intersects 
  the 
  bluffs 
  of 
  the 
  Illinois, 
  the 
  

   main 
  limestones 
  are 
  separated 
  by 
  only 
  about 
  two 
  feet 
  of 
  greenish- 
  

   colored 
  shales, 
  but 
  in 
  descending 
  the 
  river 
  bluffs 
  toward 
  Peru, 
  the 
  

   shale 
  increases 
  to 
  a 
  thickness 
  of 
  8 
  or 
  10 
  feet. 
  The 
  following 
  sec- 
  

   tion 
  was 
  made 
  along 
  the 
  river 
  bluff 
  in 
  the 
  vicinity 
  of 
  Peru 
  : 
  

  

  Ft. 
  In. 
  

  

  No. 
  1. 
  Upper 
  limestone 
  .10 
  to 
  12 
  

  

  No. 
  2. 
  Green 
  and 
  purple 
  shales 
  6 
  to 
  8 
  

  

  No. 
  3. 
  Lower 
  division 
  of 
  main 
  limestone 
  6 
  to 
  8 
  

  

  No. 
  4. 
  Bituminous 
  shale 
  1 
  6 
  

  

  No. 
  5. 
  Gray, 
  brown 
  and 
  green 
  shales 
  •. 
  8 
  

  

  No. 
  6. 
  Impure 
  coal 
  t> 
  

  

  No. 
  7. 
  Gray 
  and 
  green 
  shales 
  12 
  to 
  15 
  

  

  No. 
  8. 
  Nodular 
  limestone 
  4 
  to 
  5 
  

  

  No. 
  9. 
  Green 
  nodular 
  shale 
  12tol5 
  

  

  No. 
  10. 
  Hard 
  gray 
  limestone 
  2 
  to 
  3 
  

  

  No. 
  11. 
  Green 
  shale 
  (exposed) 
  2 
  

  

  No. 
  12. 
  Unexposed 
  to 
  river 
  level 
  15 
  to 
  20 
  

  

  No. 
  1 
  of 
  this 
  section 
  is 
  the 
  main 
  quarry 
  rock 
  used 
  as 
  a 
  building 
  

   stone 
  in 
  LaSalle 
  and 
  Peru. 
  It 
  is 
  a 
  compact 
  gray 
  limestone, 
  con- 
  

   siderably 
  stained 
  with 
  the 
  oxide 
  of 
  iron, 
  and 
  resembles 
  the 
  limestone 
  

  

  