﻿24 
  Geological 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  Mississippi 
  as 
  far 
  as 
  Memphis 
  and 
  the 
  Red 
  to 
  Shreveport. 
  

  

  To 
  account 
  for 
  the 
  occurrence 
  of 
  the 
  Orange 
  Sand 
  as 
  seen 
  in 
  

   Louisiana 
  the 
  conclusion 
  is 
  reached 
  that 
  ' 
  ' 
  in 
  late 
  Quaternary 
  

   times 
  the 
  Gulf 
  coast 
  has 
  suffered 
  a 
  depression 
  to 
  the 
  extent 
  of 
  

   at 
  least 
  nine 
  hundred 
  feet 
  (perhaps 
  more), 
  and 
  during 
  the. 
  

   Terrace 
  epoch, 
  a 
  contrarj- 
  motion 
  of 
  about 
  half 
  that 
  amount." 
  

  

  ' 
  ' 
  The 
  features 
  of 
  the 
  Grand 
  Gulf 
  group 
  in 
  Louisiana 
  are 
  almost 
  

   absolutely 
  identical 
  with 
  those 
  prevailing 
  in 
  Mississippi." 
  Hil- 
  

   gard 
  still 
  maintains 
  the 
  necessity 
  of 
  a 
  " 
  temporary 
  cutting 
  off 
  of 
  

   the 
  Mexican 
  Gulf 
  from 
  the 
  Atlantic 
  to 
  account 
  for 
  the 
  existence 
  

   of 
  the 
  Grand 
  Gulf 
  strata." 
  He 
  calls 
  attention 
  to 
  the 
  building 
  

   stone, 
  potter's 
  clay, 
  and 
  a 
  " 
  fine 
  white 
  and 
  exceedinglj'' 
  refrac- 
  

   tor}-, 
  semi-indurate 
  white 
  pipe-clay, 
  occurring 
  near 
  the 
  edge 
  of 
  

   the 
  Vicksburg 
  rocks 
  in 
  Catahoula 
  parish." 
  To 
  the 
  Vicksburg 
  

   group, 
  Hilgard 
  refers 
  practically 
  all 
  the 
  marine 
  Tertiary 
  of 
  the 
  

   State. 
  The 
  only 
  exception 
  is 
  the 
  localitj^ 
  of 
  the 
  Zeuglodon 
  on 
  

   the 
  Ouachita. 
  

  

  For 
  the 
  lignitiferous 
  beds 
  in 
  northern 
  Louisiana 
  he 
  proposes 
  

   the 
  name 
  of 
  Mansfield 
  group 
  and 
  correlates 
  them 
  with 
  the 
  lower 
  

   portions 
  of 
  the 
  Vicksburg 
  bluff. 
  

  

  In 
  discussing 
  the 
  " 
  Salines 
  of 
  Northern 
  Louisiana" 
  Hilgard 
  

   refers 
  to 
  the 
  method 
  of 
  obtaining 
  brine 
  by 
  sinking 
  shallow 
  wells 
  

   '15 
  or 
  20 
  feet 
  deep, 
  sometimes 
  by 
  drilling 
  deeper 
  wells, 
  even 
  iioo 
  

   feet 
  and 
  occasionally 
  obtaining 
  an 
  artesian 
  supply 
  of 
  brine. 
  The 
  

   records 
  of 
  these 
  borings 
  are 
  unfortunately 
  lost. 
  "But 
  in 
  one 
  

   case 
  at 
  least 
  the 
  pile 
  of 
  borings, 
  in 
  others 
  tradition 
  testifies 
  that 
  

   calcareous 
  or 
  gypseous 
  materials 
  were 
  met 
  with 
  all 
  the 
  way 
  down. 
  

   This 
  fact, 
  coupled 
  with 
  the 
  lithological 
  character 
  of 
  the 
  latter 
  

   (which 
  is 
  foreign 
  to 
  all 
  the 
  Tertiary 
  groups 
  known 
  to 
  me) 
  and 
  the 
  

   'find' 
  of 
  several 
  individuals 
  of 
  Exogyra 
  costata 
  and 
  Gryphcea 
  

   pitcheri 
  in 
  the 
  rubbish 
  of 
  one 
  pit, 
  suggests 
  that 
  here 
  we 
  have 
  

   not 
  local 
  Tertiary 
  basins, 
  but 
  rather 
  the 
  peaks 
  of 
  a 
  Cretaceous 
  

   ridge, 
  projecting 
  through 
  the 
  lignitic 
  Tertiary." 
  

  

  In 
  this 
  report, 
  as 
  stated 
  above, 
  Hilgard 
  describes 
  the 
  artesian 
  

   wells 
  of 
  Calcasieu. 
  They 
  " 
  are 
  located 
  on 
  two 
  small 
  islands 
  in 
  

   the 
  (fresh 
  water) 
  marsh 
  which 
  forms 
  the 
  head 
  of 
  the 
  bayou 
  

   Choupique," 
  a 
  small 
  tributary 
  of 
  the 
  Calcasieu 
  river. 
  

  

  At 
  the 
  time 
  of 
  Hilgard' 
  s 
  visit 
  the 
  well 
  being 
  sunk 
  by 
  the 
  

  

  