﻿I20 
  Geological 
  Survey 
  of 
  I^ouisiana 
  [Sect 
  

  

  1. 
  Gas 
  theory. 
  

  

  2. 
  Superincumbent 
  pressure 
  theory. 
  

  

  3. 
  Suppressed 
  spring 
  theory. 
  

  

  4. 
  Hj'draulic 
  tube 
  theory. 
  

  

  5. 
  Tide 
  and 
  current 
  theory. 
  

  

  One 
  of 
  the 
  first 
  theories 
  advanced 
  was 
  that 
  of 
  the 
  gas 
  origin.* 
  

   This 
  theory 
  attributes 
  to 
  gas 
  the 
  main 
  part 
  in 
  the 
  formation 
  of 
  the 
  

   mounds. 
  The 
  decomposition 
  of 
  the 
  vegetable 
  and 
  animal 
  matter 
  

   buried 
  in 
  the 
  delta 
  gives 
  rise 
  to 
  gas. 
  In 
  its 
  attempts 
  to 
  escape 
  

   this 
  gas 
  will 
  lift 
  the 
  upper 
  clay 
  to 
  the 
  surface 
  of 
  the 
  water 
  and 
  

   then 
  unable 
  to 
  lift 
  it 
  higher 
  will 
  break 
  through, 
  carrying 
  with 
  it 
  

   water 
  and 
  fine 
  mud. 
  

  

  The 
  theory 
  advanced 
  by 
  Lyellf 
  and 
  Hilgard|is 
  that 
  the 
  weight 
  of 
  

   the 
  material 
  now 
  being 
  thorwn 
  down 
  at 
  the 
  delta 
  on 
  the 
  fine 
  semi- 
  

   liquid 
  mud 
  deposited 
  when 
  the 
  river 
  was 
  farther 
  inland 
  will 
  tend 
  

   to 
  squeeze 
  this 
  fine 
  mud 
  from 
  under 
  the 
  crest 
  of 
  the 
  bar. 
  This 
  

   material 
  finds 
  vent 
  where 
  the 
  pressure 
  is 
  least, 
  giving 
  rise 
  to 
  

   mud-lumps. 
  

  

  The 
  other 
  theories 
  depend 
  on 
  water 
  alone 
  asa 
  formative 
  agent. 
  

   In 
  1866 
  Beuregard 
  advanced 
  the 
  following 
  theory 
  of 
  the 
  origin 
  

   of 
  the 
  mud-lumps 
  : 
  ' 
  ' 
  Now 
  if 
  a 
  tube 
  be 
  supposed 
  to 
  pass 
  from 
  

   the 
  inside 
  of 
  the 
  bar, 
  where 
  the 
  current 
  is 
  more 
  or 
  less 
  strong, 
  

   to 
  the 
  outside 
  of 
  it, 
  where 
  there 
  is 
  hardly 
  any 
  current, 
  it 
  is 
  evi- 
  

   dent 
  that 
  the 
  force 
  of 
  the 
  current 
  will 
  fill 
  this 
  tube 
  with 
  that 
  

   floating 
  mud 
  lying 
  at 
  the 
  bottom 
  of 
  the 
  river, 
  and 
  cause 
  it 
  to 
  

   issue 
  at 
  its 
  extremity 
  to 
  a 
  higher 
  or 
  lower 
  level, 
  or 
  not 
  at 
  all, 
  

   according 
  to 
  the 
  strength 
  of 
  the 
  current 
  acting 
  at 
  that 
  tirae."§ 
  

   As 
  this 
  can 
  be 
  proven 
  to 
  be 
  contrary 
  to 
  physical 
  laws 
  it 
  is 
  hardly 
  

   to 
  be 
  considered. 
  

  

  The 
  suppressed 
  spring 
  theory 
  holds 
  that 
  water 
  originating 
  at 
  

   a 
  much 
  higher 
  level 
  finds 
  vent 
  here. 
  Forshey 
  supposed 
  that 
  for 
  

  

  *Sidell, 
  Report 
  to 
  Capt.Talcott, 
  1839, 
  in 
  Humphreys 
  and 
  Abbott's 
  Report 
  

   on 
  the 
  Hydraulics 
  and 
  Physics 
  of 
  the 
  Mississippi 
  River, 
  Appendix 
  A, 
  i860 
  ; 
  

   Drake, 
  A 
  Systematic 
  Treatise 
  on 
  the 
  Principal 
  Diseases 
  of 
  the 
  Interior 
  Val- 
  

   ley 
  of 
  North 
  America, 
  Con. 
  1850, 
  pp. 
  93-94; 
  Long, 
  35th 
  Cong. 
  1st 
  Sess., 
  

   Ex. 
  Doc. 
  No. 
  139, 
  p.' 
  41 
  ; 
  Hopkins, 
  ist 
  An. 
  Rep. 
  Geol. 
  Surv. 
  La., 
  p. 
  82,1870. 
  

  

  f 
  Prin. 
  Geol., 
  loth 
  ed., 
  1868, 
  vol. 
  i, 
  p. 
  449- 
  

  

  t 
  Amer. 
  Jour. 
  Sci., 
  3d 
  series, 
  vol. 
  i, 
  1871, 
  pp. 
  238-246, 
  356-368, 
  425-435- 
  

  

  ^35th 
  Cong., 
  1st 
  Sess., 
  House 
  Ex. 
  Doc, 
  No. 
  97, 
  vol. 
  12, 
  pp. 
  6-7, 
  1866. 
  

  

  