﻿Ill] 
  Shrevbport 
  Area 
  : 
  The 
  Raft 
  163 
  

  

  of 
  the 
  river. 
  The 
  following 
  table 
  gives 
  the 
  accumulation 
  in 
  the 
  

   different 
  periods 
  : 
  

  

  From 
  1820 
  to 
  1838 
  16 
  miles 
  (Lieut. 
  Col. 
  Long*). 
  

  

  1839 
  to 
  1857 
  14 
  miles 
  (Lieut. 
  Col. 
  Longf 
  ). 
  

  

  1857 
  to 
  1872 
  13.5 
  miles 
  (Lieut. 
  WoodruffJ). 
  

  

  Of 
  this 
  space 
  only 
  from 
  a 
  third 
  to 
  a 
  half 
  was 
  occupied 
  by 
  timber. 
  

  

  Formation 
  of 
  lakes. 
  — 
  As 
  the 
  head 
  of 
  the 
  raft 
  moves 
  up 
  the 
  val- 
  

   ley 
  it 
  will 
  obstruct 
  the 
  outlets 
  of 
  the 
  bottom 
  basins 
  and 
  tributary 
  

   stream 
  valleys 
  and 
  by 
  preventing 
  the 
  discharge 
  of 
  the 
  streams 
  

   convert 
  them 
  into 
  lakes. 
  The 
  size 
  of 
  these 
  lakes 
  will 
  be 
  further 
  

   increased 
  in 
  two 
  ways 
  : 
  (i) 
  the 
  checking 
  of 
  the 
  river 
  current 
  in 
  

   the 
  raft 
  region 
  will 
  result 
  in 
  the 
  deposition 
  of 
  great 
  amounts 
  of 
  

   sediment. 
  This 
  will 
  build 
  up 
  the 
  bed 
  and 
  banks 
  of 
  the 
  river 
  and 
  

   so 
  increase 
  the 
  height 
  of 
  the 
  dam 
  at 
  the 
  mouth 
  of 
  the 
  lake 
  ; 
  (2) 
  

   as 
  the 
  raft 
  continues 
  its 
  movement 
  up 
  stream 
  outlet 
  bayous 
  will 
  

   be 
  formed 
  and 
  a 
  porton 
  of 
  the 
  river 
  current 
  deflected 
  into 
  these 
  

   lakes. 
  

  

  Retreat 
  of 
  the 
  foot 
  of 
  the 
  raft. 
  — 
  For 
  a 
  number 
  of 
  years 
  after 
  its 
  

   formation 
  and 
  until 
  enough 
  logs 
  decay 
  in 
  the 
  lower 
  end 
  to 
  allow 
  

   the 
  remaining 
  logs 
  to 
  be 
  floated 
  off 
  in 
  high 
  water 
  the 
  foot 
  of 
  the 
  

   raft 
  will 
  remain 
  stationary. 
  The 
  rate 
  of 
  retreat 
  will 
  be 
  even 
  

   more 
  irregular 
  than 
  the 
  advance 
  of 
  the 
  head 
  of 
  the 
  raft 
  because 
  

   a 
  snag 
  or 
  two 
  of 
  very 
  resisting 
  wood 
  may 
  be 
  able 
  to 
  keep 
  back 
  a 
  

   large 
  amount 
  of 
  decayed 
  raft 
  for 
  many 
  years 
  and 
  even 
  after 
  their 
  

   decay 
  several 
  years 
  may 
  elapse 
  before 
  a 
  sufificiently 
  large 
  flood 
  

   will 
  occur 
  to 
  occasion 
  enough 
  current 
  at 
  the 
  foot 
  of 
  the 
  raft 
  to 
  

   float 
  the 
  fragments 
  away. 
  

  

  The 
  information 
  bearing 
  on 
  the 
  rate 
  of 
  decay 
  of 
  the 
  foot 
  of 
  

   the 
  raft 
  is 
  not 
  so 
  full 
  or 
  satisfactory 
  as 
  that 
  bearing 
  on 
  the 
  rate 
  

   of 
  advance 
  of 
  the 
  head. 
  According 
  to 
  the 
  letter 
  of 
  Dr. 
  John 
  

   Sibley, 
  quoted 
  above, 
  in 
  1805 
  the 
  foot 
  of 
  the 
  raft 
  was 
  at 
  the 
  

   Campti 
  settlement. 
  At 
  the 
  beginning 
  of 
  Shreve's 
  work 
  in 
  1833 
  

   the 
  foot 
  was 
  just 
  above 
  Loggy 
  bayou, 
  a 
  distance 
  of 
  about 
  59 
  

   miles 
  by 
  the 
  charts 
  of 
  the 
  Red 
  River 
  Survey. 
  This 
  would 
  give 
  

   an 
  average 
  annual 
  rate 
  of 
  decay 
  of 
  about 
  2\ 
  miles. 
  

  

  * 
  27th 
  Cong., 
  1st 
  Sess., 
  Senate 
  Ex. 
  Doc, 
  vol. 
  i, 
  No. 
  64, 
  p. 
  10, 
  1841. 
  

   f 
  35th 
  Cong., 
  2d 
  Sess., 
  Senate 
  Ex. 
  Doc, 
  vol. 
  3, 
  p. 
  1053, 
  1859. 
  

   J 
  43d 
  Cong., 
  1st 
  Sess., 
  House 
  Ex. 
  Doc, 
  vol. 
  2, 
  part 
  2, 
  p. 
  648. 
  

  

  