﻿Ill] 
  Shreveport 
  Area 
  : 
  Mounds 
  195 
  

  

  embankments 
  were 
  used 
  for 
  nothing 
  but 
  cultivation, 
  and 
  that 
  

   they 
  are 
  intended 
  to 
  counteract 
  the 
  humidity 
  of 
  the 
  soil, 
  still 
  the 
  

   greatest 
  obstacle 
  with 
  which 
  the 
  tillers 
  of 
  the 
  soil 
  of 
  the 
  plains 
  of 
  

   the 
  Mississippi 
  valley 
  have 
  to 
  contend. 
  

  

  The 
  last 
  two 
  theories 
  account 
  for 
  the 
  origin 
  of 
  the 
  mounds 
  by 
  

   erosion 
  ; 
  the 
  first 
  by 
  a 
  rapid 
  rush 
  of 
  waters 
  ; 
  the 
  second 
  by 
  differ- 
  

   ential 
  erosion.* 
  Neither 
  seems 
  to 
  be 
  at 
  all 
  sustained 
  by 
  the 
  facts. 
  

  

  The 
  OIvDEr 
  Tertiary 
  

  

  Previous 
  work. 
  — 
  A 
  number 
  of 
  geologists 
  have 
  done 
  work 
  on 
  

   parts 
  of 
  the 
  older 
  Tertiary 
  which 
  border 
  the 
  bottom 
  lands 
  dis- 
  

   cussed 
  in 
  this 
  paper. 
  By 
  far 
  the 
  most 
  careful 
  and 
  detailed 
  

   observations 
  on 
  the 
  bordering 
  hills 
  were 
  made 
  by 
  Mr. 
  H. 
  C. 
  

   Collins, 
  one 
  of 
  Lieut. 
  Woodruff's 
  assistants 
  on 
  the 
  Red 
  River 
  

   Raft 
  Survey 
  of 
  1871-1872.! 
  Although 
  not 
  a 
  professional 
  

   geologist 
  or 
  a 
  man 
  who 
  had 
  had 
  much 
  geological 
  training, 
  his 
  

   observations 
  have 
  great 
  value 
  as 
  being 
  a 
  concise 
  statement 
  of 
  

   what 
  he 
  saw. 
  This 
  report 
  was 
  not 
  known 
  to 
  the 
  writer 
  while 
  he 
  

   was 
  in 
  the 
  field 
  so 
  no 
  investigation 
  was 
  made 
  of 
  Collins' 
  

   reported 
  find 
  of 
  the 
  Cretaceous 
  fossil, 
  ''"Nautilus 
  dekayi 
  and 
  

   another 
  fossil 
  ' 
  ' 
  in 
  the 
  bluff 
  at 
  the 
  Cypress 
  brake 
  between 
  

   Henderson's 
  Mills 
  and 
  Albany, 
  and 
  at 
  Irving's 
  bluff. 
  Prof. 
  

   Harris 
  has 
  suggested 
  that 
  he 
  has 
  in 
  all 
  probability 
  mistaken 
  

   Nautilus 
  dekayi 
  yiorX.., 
  ior 
  Endimatoceras 
  ulrzc/ii 
  White, 
  and 
  that 
  

   the 
  beds 
  are 
  probably 
  Midway 
  Eocene. 
  

  

  Besides 
  Collins, 
  Hopkins, 
  J 
  Johnson, 
  § 
  lycrch 
  || 
  and 
  Clendenin^ 
  

  

  * 
  Brief 
  statements 
  of 
  this 
  latter 
  theory 
  are 
  given 
  by 
  David 
  Dale 
  Owen, 
  

   Second 
  Report 
  of 
  a 
  Geol. 
  Reconnaissance 
  of 
  part 
  of 
  the 
  State 
  of 
  Arkansas, 
  

   Phila., 
  i860, 
  p. 
  144, 
  and 
  Otto 
  Lerch, 
  Bull. 
  La. 
  State 
  Expt. 
  Sta. 
  , 
  Geol. 
  and 
  

   Agri., 
  part 
  II, 
  1893, 
  p. 
  106. 
  

  

  f 
  Geologic 
  Notes 
  of 
  Assistant 
  H. 
  C. 
  Collins. 
  An. 
  Rept., 
  Chief 
  of 
  Eng,, 
  

   for 
  1873, 
  vol. 
  I, 
  pp. 
  651-664, 
  1873 
  ; 
  also 
  43d 
  Cong., 
  ist 
  Sess., 
  vol. 
  2, 
  part 
  2, 
  

   pp. 
  651-664, 
  1873. 
  

  

  t 
  Second 
  An. 
  Rept. 
  of 
  the 
  Geol. 
  Snrv. 
  of 
  La. 
  by 
  F. 
  V. 
  Hopkins, 
  1871, 
  

   pp. 
  9, 
  22. 
  Also 
  First 
  Annual 
  Report 
  of 
  the 
  Geol. 
  Survey 
  of 
  La., 
  by 
  F. 
  V 
  

   Hopkins, 
  pp. 
  86, 
  89, 
  1870. 
  

  

  § 
  The 
  Iron 
  Regions 
  of 
  Northern 
  Louisiana 
  and 
  Eastern 
  Texas 
  by 
  L. 
  C. 
  

   Johnston. 
  5uth 
  Cong., 
  ist 
  Sess., 
  House 
  Ex. 
  Doc, 
  No. 
  195, 
  vol. 
  26, 
  pp. 
  17- 
  

   19, 
  22, 
  34-37, 
  1888. 
  

  

  I 
  A 
  Preliminary 
  Report 
  Upon 
  the 
  Hills 
  of 
  Louisiana, 
  North 
  of 
  the 
  

   Vicksburg, 
  Shreveport 
  and 
  Pacific 
  Railroad, 
  by 
  Otto 
  Lerch. 
  Bull. 
  La. 
  

   State 
  Ex. 
  Sta.; 
  Geol. 
  and 
  Agr. 
  , 
  part 
  i, 
  1892, 
  pp. 
  18-19. 
  

  

  ^W. 
  W. 
  Clendenin 
  spent 
  two 
  seasons 
  working 
  on 
  the 
  Geology 
  of 
  Caddo 
  

   parish 
  but 
  published 
  no 
  report. 
  

  

  