﻿144 
  Geological 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  overflows 
  the 
  greater 
  amount 
  of 
  sedimentation 
  takes 
  place 
  not 
  

   far 
  from 
  the 
  river 
  banks 
  and 
  hence 
  tends 
  in 
  the 
  course 
  of 
  a 
  long 
  

   period 
  of 
  time 
  to 
  elevate 
  the 
  strips 
  of 
  land 
  immediately 
  border- 
  

   ing 
  the 
  streams. 
  

  

  Stratigraphy 
  

   Eocene 
  

  

  That 
  the 
  reader 
  may 
  have 
  a 
  better 
  conception 
  of 
  the 
  strati- 
  

   graphy 
  of 
  this 
  township, 
  an 
  ideal 
  section 
  has 
  been 
  placed 
  

   beneath 
  the 
  map, 
  showing 
  the 
  way 
  the 
  various 
  series 
  of 
  deposits 
  

   lie 
  along 
  a 
  line 
  passing 
  east 
  and 
  west 
  through 
  Natchitoches 
  from 
  

   the 
  points 
  W 
  to 
  E, 
  as 
  indicated 
  on 
  the 
  map. 
  

  

  Beneath 
  the 
  whole 
  region, 
  at 
  a 
  depth 
  of 
  probably 
  not 
  over 
  

   800 
  or 
  1,000 
  feet, 
  lie 
  Cretaceous 
  deposits. 
  Some 
  account 
  of 
  local 
  

   outcrops 
  of 
  this 
  series 
  has 
  already 
  been 
  given 
  on 
  p. 
  52., 
  ei 
  seq. 
  

  

  Lignitic 
  stage. 
  — 
  The 
  oldest 
  visible 
  beds 
  in 
  this 
  section 
  are 
  the 
  

   lignitic 
  sands 
  and 
  clays, 
  appearing 
  for 
  the 
  most 
  part 
  in 
  the 
  north- 
  

   western 
  portion 
  of 
  the 
  township 
  though 
  occurring 
  elsewhere, 
  as 
  

   for 
  example, 
  in 
  a 
  branch 
  or 
  creek 
  near 
  the 
  southwest 
  corner 
  of 
  

   the 
  township 
  by 
  the 
  roadside. 
  Here 
  lignitic 
  and 
  ferruginous 
  

   sands 
  are 
  to 
  be 
  seen 
  in 
  the 
  south 
  bank 
  of 
  the 
  creek. 
  But 
  par- 
  

   ticularly 
  abundant 
  are 
  the 
  light 
  yellowish 
  calcerous 
  concretions 
  

   of 
  various 
  shapes 
  and 
  sizes. 
  So 
  abundant 
  are 
  they 
  that 
  they 
  

   have 
  been 
  burned 
  for 
  lime. 
  

  

  Probably 
  all 
  the 
  sands 
  and 
  clays 
  forming 
  the 
  hills 
  west 
  of 
  

   Mill 
  bayou 
  are 
  of 
  this 
  age. 
  The 
  same 
  remark 
  applies 
  to 
  hilly 
  

   lands 
  west 
  of 
  the 
  railroad 
  and 
  north 
  of 
  Sibley's 
  lake. 
  

  

  Three-fourths 
  of 
  a 
  mile 
  north 
  of 
  Natchitoches 
  bridge 
  the 
  

   bluff 
  as 
  shown 
  on 
  PI. 
  13, 
  exhibits 
  at 
  base 
  20-25 
  feet 
  of 
  purplish 
  

   clay 
  with 
  sand 
  parting, 
  all 
  dipping 
  southward. 
  

  

  Slightly 
  farther 
  to 
  the 
  right, 
  in 
  a 
  little 
  ravine, 
  a 
  bed 
  of 
  light- 
  

   colored, 
  compact 
  sand 
  is 
  exposed, 
  showing 
  at 
  least 
  a 
  thickness 
  

   of 
  15 
  feet. 
  This 
  bed 
  is 
  for 
  the 
  most 
  part 
  covered 
  by 
  the 
  talus 
  

   at 
  the 
  base 
  of 
  the 
  bluff 
  shown 
  in 
  the 
  illustration. 
  

  

  It 
  is 
  however, 
  at 
  Grand 
  Ecore, 
  a 
  place 
  on 
  Red 
  river, 
  a 
  few 
  

   miles 
  north 
  of 
  Natchitoches 
  that 
  the 
  Lignitic 
  beds 
  are 
  best 
  

   exposed. 
  A 
  section 
  of 
  the 
  same 
  has 
  already 
  been 
  given 
  on 
  p. 
  71- 
  

  

  In 
  the 
  depths 
  of 
  little 
  ravines 
  in 
  the 
  northwestern 
  part 
  of 
  this 
  

  

  