﻿34 
  

  

  Geological 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  The 
  Jackson 
  group 
  is 
  next 
  taken 
  up 
  and 
  traced 
  from 
  Grand- 
  

   view, 
  on 
  the 
  Ouachita, 
  to 
  Montgomery, 
  on 
  the 
  Red. 
  The 
  latter 
  

   locality, 
  the 
  most 
  important 
  Jackson 
  deposit 
  in 
  the 
  State, 
  was 
  

   brought 
  to 
  the 
  attention 
  of 
  the 
  scientific 
  world 
  by 
  the 
  transmis- 
  

   sion 
  to 
  the 
  State 
  Military 
  Academy 
  of 
  a 
  vertebra 
  of 
  Zeuglodon 
  

   by 
  Judge 
  A. 
  V. 
  Ragan, 
  the 
  owner 
  of 
  the 
  bluff 
  and 
  plantation. 
  

   He 
  notes 
  (p. 
  94) 
  the 
  occurrence 
  of 
  Orbitoides 
  inantelli, 
  a. 
  typical 
  

   Vicksburg 
  species, 
  in 
  the 
  Jackson 
  beds 
  at 
  this 
  locality. 
  Many 
  

   of 
  the 
  more 
  important 
  Lower 
  Claiborne 
  localities, 
  as 
  known 
  

   to-day, 
  were 
  visited 
  by 
  Hopkins 
  and 
  referred 
  to 
  the 
  Jackson 
  

   period. 
  

  

  The 
  " 
  Vicksburg 
  formation 
  " 
  he 
  traces 
  from 
  " 
  near 
  the 
  Oua- 
  

   chita 
  to 
  nineteen 
  miles 
  southwest 
  of 
  Natchitoches 
  " 
  including 
  

   much 
  that 
  is 
  now 
  known 
  to 
  be 
  Lower 
  Claiborne. 
  

  

  The 
  Grand 
  Gulf 
  is 
  then 
  taken 
  up 
  and 
  its 
  characters, 
  extent, 
  

   out-crops, 
  etc., 
  given. 
  Sections 
  are 
  given 
  at 
  Harrisonburg, 
  

   Chalk 
  hills 
  and 
  Alexandria. 
  

  

  The 
  deposits 
  of 
  the 
  ' 
  ' 
  Drift 
  Period 
  ' 
  ' 
  are 
  then 
  discussed 
  as 
  

   regards 
  geographical 
  distribution. 
  He 
  makes 
  the 
  following 
  gen- 
  

   eral 
  statements 
  : 
  "The 
  country 
  covered 
  by 
  the 
  drift, 
  i. 
  e., 
  the 
  

   areas 
  of 
  the 
  Grand 
  Gulf, 
  much 
  of 
  the 
  Jackson 
  and 
  Vicksburg, 
  

   and 
  almost 
  all 
  of 
  the 
  Mansfield 
  groups, 
  comprises 
  the 
  upland 
  

   region 
  of 
  the 
  State. 
  It 
  is, 
  in 
  general, 
  broken 
  and 
  hilly, 
  the 
  

   height 
  of 
  the 
  hills 
  depending 
  principally 
  on 
  the 
  underlying 
  Ter- 
  

   tiarj^ 
  strata. 
  The 
  highest 
  are 
  on 
  the 
  territory 
  of 
  the 
  Mansfield 
  

   group, 
  between 
  Shreveport 
  and 
  Monroe 
  ; 
  but 
  the 
  Harrisonburg, 
  

   Cloutierville 
  and 
  Kisatche 
  hills 
  are 
  of 
  Grand 
  Gulf 
  age, 
  as 
  we 
  

   have 
  seen 
  already. 
  The 
  intervening 
  region 
  of 
  the 
  Jackson 
  and 
  

   Vicksburg 
  are 
  lower, 
  and 
  are 
  often 
  entirely 
  bare 
  of 
  the 
  drift, 
  as 
  

   is 
  the 
  case 
  also 
  with 
  the 
  marly 
  regions 
  of 
  the 
  Grand 
  Gulf. 
  Per- 
  

   haps 
  the 
  presence 
  of 
  lime 
  in 
  the 
  soil 
  renders 
  it 
  more 
  penetrable 
  

   by 
  water 
  and 
  therefore 
  more 
  subject 
  to 
  denudation, 
  so 
  that 
  an 
  

   oceanic 
  current 
  carrying 
  detritus, 
  would 
  deposit 
  it 
  most 
  heavily 
  

   where 
  there 
  was 
  the 
  least 
  lime. 
  Whatever 
  the 
  explanation 
  may 
  

   be, 
  this 
  appears 
  to 
  have 
  been 
  the 
  fact." 
  

  

  Hopkin's 
  Second 
  Annual 
  Report 
  of 
  the 
  Geological 
  Survey 
  of 
  

   Louisiana 
  was 
  presented 
  to 
  the 
  General 
  Assembly 
  late 
  in 
  1870 
  

   and 
  published 
  in 
  187 
  1. 
  It 
  is 
  accompanied 
  by 
  a 
  colored 
  map 
  of 
  

  

  