﻿72 
  Geoi^ogicaIv 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  acterized 
  by 
  a 
  Lower 
  Lignitic 
  fauna 
  including 
  Ostrea 
  thirscs 
  var., 
  

   Levifusus 
  indentiis, 
  and 
  other 
  species 
  characteristic 
  of 
  this 
  

   horizon. 
  

  

  Specimens 
  from 
  Sodus, 
  from 
  concretions 
  presumably 
  of 
  the 
  

   same 
  horizon 
  were 
  scarcely 
  identifiable. 
  

  

  One 
  the 
  north-east 
  one-fourth 
  of 
  Section 
  2, 
  9 
  N., 
  12 
  W. 
  

   Sabine 
  parish, 
  mineral 
  water 
  is 
  obtained 
  from 
  Ferrell's 
  well. 
  

   Dr. 
  J. 
  E. 
  Mumford 
  collected 
  several 
  ferruginous, 
  clay 
  concre- 
  

   tions 
  near 
  this 
  well 
  that 
  show 
  an 
  interesting, 
  though 
  poorly 
  

   preserved 
  marine 
  fauna. 
  Venericardia 
  planicosta, 
  Yoldia 
  kindlei, 
  

   Vohitilithes 
  petrosus, 
  Calyptraphorus 
  , 
  Levifusus 
  Pleiiroioma 
  

   silicata, 
  and 
  other 
  Pleurotomce, 
  seemingly 
  of 
  a 
  lowest 
  Lignitic 
  

   or 
  Midway 
  aspect. 
  

  

  Mansfield. 
  — 
  This 
  region 
  was 
  first 
  described 
  geologically 
  by 
  

   Hilgard 
  in 
  1869 
  and 
  much 
  more 
  fully 
  by 
  the 
  same 
  author 
  in 
  

   1873. 
  He 
  called 
  particular 
  attention 
  to 
  the 
  limestone, 
  concre- 
  

   tionary 
  layers 
  so 
  often 
  seen 
  in 
  this 
  portion 
  of 
  the 
  State, 
  and 
  con- 
  

   cluded 
  from 
  the 
  fact 
  that 
  they 
  contain 
  fossil 
  leaves 
  that 
  they 
  

   were 
  of 
  fresh 
  water 
  origin. 
  This 
  seemed 
  such 
  a 
  departure 
  

   from 
  the 
  ordinar}^ 
  run 
  of 
  lignitic 
  Tertiary 
  beds 
  that 
  he 
  gave 
  a 
  

   new 
  name 
  to 
  the 
  group 
  of 
  sands 
  and 
  clays 
  containing 
  these 
  con- 
  

   cretions, 
  calling 
  them 
  the 
  Mansfield 
  group. 
  (See 
  further 
  under 
  

   Historic 
  review.) 
  

  

  The 
  nature 
  of 
  the 
  material 
  that 
  underlies 
  the 
  soils 
  in 
  this 
  gen- 
  

   eral 
  region 
  is 
  well 
  shown 
  by 
  the 
  following 
  section 
  made 
  from 
  an 
  

   outcrop 
  in 
  the 
  gorge 
  just 
  west 
  of 
  the 
  town. 
  

  

  5. 
  Soil 
  and 
  red 
  sand 
  5 
  ft. 
  

  

  4. 
  Sand 
  with 
  iron 
  streaks 
  10 
  ft. 
  

  

  3. 
  Sand 
  with 
  a 
  few 
  light 
  bluish 
  clay 
  streaks 
  5 
  ft. 
  

  

  2. 
  Very 
  light, 
  or 
  yellowish 
  calcareous 
  concretions 
  2 
  ft. 
  

  

  I. 
  Sandy, 
  laminated, 
  sands, 
  with 
  iron 
  streaks 
  above 
  ; 
  light 
  

  

  sands, 
  medially 
  ; 
  bluish 
  laminated 
  clays 
  below 
  30 
  ft. 
  

  

  As 
  might 
  be 
  anticipated 
  by 
  the 
  character 
  of 
  the 
  rocks 
  exposed 
  

   in 
  this 
  section, 
  the 
  hill 
  land 
  about 
  Mansfield 
  is 
  decidedly 
  sandy. 
  

   But 
  there 
  are 
  broad 
  bottom 
  lands 
  adjacent 
  to 
  stream 
  courses, 
  of 
  

   a 
  more 
  clayey 
  and 
  loamy 
  character, 
  and 
  very 
  productive. 
  To 
  the 
  

   southwest 
  and 
  west, 
  calcareous 
  black 
  land 
  prairies 
  are 
  reported. 
  

  

  At 
  Logansport 
  on 
  the 
  Sabine 
  extensive 
  deposits 
  of 
  lignite 
  are 
  

  

  