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  Geological 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  regarding 
  the 
  Vicksburg 
  outcroppings 
  by 
  the 
  little 
  orbitolite 
  

   specimens 
  in 
  the 
  Lower 
  Claiborne 
  which 
  he 
  takes 
  to 
  be 
  Orbitoides 
  

   mantelli. 
  The 
  salt 
  works 
  in 
  Northern 
  Louisiana 
  are 
  well 
  

   described, 
  likewise 
  the 
  so-called 
  marble 
  and 
  limestones. 
  The 
  

   Grand 
  Gulf 
  beds 
  at 
  Harrisonburg 
  are 
  well 
  described. 
  In 
  the 
  

   recapitulation 
  he 
  gives 
  again 
  the 
  Calcasieu 
  wells. 
  

  

  In 
  1874, 
  Hilgard 
  published 
  a 
  " 
  Note 
  on 
  Lignite 
  Beds 
  and 
  

   Their 
  Under-Clays 
  " 
  in 
  the 
  American 
  Journal 
  of 
  Science.* 
  In 
  

   the 
  course 
  of 
  this 
  note 
  he 
  says 
  : 
  " 
  The 
  cause 
  of 
  this 
  complete 
  

   obliteration 
  of 
  spongy 
  roots 
  or 
  spongy 
  parts 
  of 
  roots 
  is 
  doubtless 
  

   to 
  be 
  sought 
  in 
  the 
  oxidizing 
  influence 
  of 
  ferruginous 
  solutions 
  

   percolating 
  from 
  above, 
  and 
  the 
  subsequent 
  action 
  of 
  pressure 
  

   on 
  the 
  yielding 
  mass." 
  * 
  * 
  * 
  "That 
  another 
  phase 
  of 
  the 
  

   same 
  agencies 
  has 
  been 
  instrumental 
  in 
  obliterating 
  the 
  teeming 
  

   fauna 
  of 
  the 
  Port 
  Hudson 
  beds, 
  whose 
  character 
  can 
  now 
  be 
  

   studied 
  only 
  in 
  a 
  few 
  limited 
  localities, 
  I 
  have 
  already 
  shown 
  

   (Smith. 
  Contr. 
  Knowl., 
  No. 
  248, 
  p. 
  12). 
  And 
  there 
  can 
  be 
  little 
  

   doubt 
  that 
  the 
  absolute 
  dearth 
  of 
  organic 
  remains 
  which 
  has 
  

   thus 
  far 
  frustrated 
  all 
  my 
  attempts 
  to 
  gain 
  a 
  definite 
  clue 
  to 
  the 
  

   age 
  of 
  the 
  Grand 
  Gulf 
  beds 
  of 
  the 
  Gulf 
  border, 
  is 
  largely 
  due 
  

   to 
  the 
  same 
  cause, 
  and 
  not 
  to 
  the 
  conversion 
  of 
  the 
  Mexico 
  Gulf 
  

   into 
  a 
  dead 
  sea 
  during 
  the 
  Post-Eocene 
  Tertiary 
  period." 
  

  

  In 
  arguing 
  against 
  the 
  aeolian 
  origin 
  of 
  the 
  Loess, 
  Hilgard 
  

   statest 
  that 
  in 
  Louisiana 
  representative 
  deposits 
  are 
  quite 
  dis- 
  

   tinctly 
  stratified. 
  

  

  In 
  1 
  88 
  1, 
  Hilgard 
  contributed 
  an 
  article 
  on 
  " 
  the 
  Later 
  Tertiary 
  

   of 
  the 
  Gulf 
  of 
  Mexico" 
  to 
  the 
  American 
  Journal 
  of 
  Science. 
  t 
  

   This 
  article 
  is 
  inspired 
  by 
  the 
  recent 
  publication 
  of 
  the 
  Coast 
  

   Survey 
  charf'Soundings 
  in 
  the 
  Gulf 
  of 
  Mexico" 
  and 
  the 
  observa- 
  

   tions 
  of 
  Smith 
  on 
  the 
  geology 
  of 
  Florida. 
  

  

  On 
  his 
  map 
  the 
  northern 
  edge 
  of 
  the 
  Grand 
  Gulf 
  formation 
  is 
  

   made 
  to 
  curve 
  around 
  in 
  Alabama 
  and 
  ' 
  ' 
  run 
  out 
  ' 
  ' 
  into 
  the 
  Gulf 
  

   of 
  Mexico 
  at 
  about 
  the 
  western 
  extremity 
  of 
  Florida. 
  It 
  thus 
  

   seems 
  to 
  have 
  some 
  relationship 
  to 
  the 
  abrupt 
  descent 
  in 
  

  

  *Vol. 
  7, 
  pp. 
  208-210. 
  

  

  fAm. 
  Jour. 
  Sci., 
  vol. 
  18, 
  1879, 
  p. 
  107. 
  

  

  t 
  Vol. 
  22, 
  pp. 
  58-65, 
  map. 
  

  

  