﻿II] 
  General 
  Geology: 
  Quaternary 
  119 
  

  

  salt 
  mass 
  is 
  in 
  the 
  shape 
  of 
  an 
  elongate 
  dome. 
  On 
  Belle 
  Isle 
  

   fossiliferous 
  surface 
  beds 
  show 
  the 
  same 
  dip 
  as 
  the 
  surface 
  of 
  

   the 
  salt 
  and 
  where 
  the 
  apex 
  of 
  the 
  dome 
  was 
  entered 
  by 
  the 
  

   mine 
  shaft 
  the 
  internal 
  structure 
  and 
  bedding 
  of 
  the 
  salt 
  seems 
  

   to 
  show 
  that 
  the 
  mass 
  owes 
  its 
  shape 
  not 
  to 
  erosion 
  but 
  folding. 
  

   On 
  Petite 
  Anse 
  the 
  salt 
  contains 
  certain 
  thin, 
  black, 
  slightly 
  

   gypseous 
  bands 
  of 
  salt 
  which 
  dip 
  about 
  80° 
  S. 
  E. 
  From 
  this 
  it 
  

   is 
  inferred 
  that 
  there 
  is 
  in 
  this 
  vicinity 
  either 
  a 
  fault 
  or 
  a 
  very 
  

   steep 
  anticline. 
  

  

  The 
  date 
  of 
  the 
  formation 
  of 
  the 
  similar 
  domes 
  of 
  Cretaceous 
  

   material 
  in 
  northern 
  Louisiana 
  is 
  yet 
  an 
  open 
  question. 
  There 
  

   seems 
  to 
  be 
  no 
  evidence 
  to 
  prove 
  or 
  disprove 
  that 
  they 
  were 
  

   formed 
  at 
  the 
  same 
  time 
  as 
  the 
  Five 
  Islands. 
  It 
  is 
  hard 
  to 
  

   believe 
  that 
  they 
  were 
  formed 
  so 
  recently. 
  The 
  disturbed 
  con- 
  

   dition 
  and 
  the 
  dip 
  of 
  the 
  L,ovver 
  Claiborne 
  beds 
  on 
  the 
  northern 
  

   part 
  of 
  the 
  Winnfield 
  anticline 
  indicate 
  that 
  a 
  part 
  of 
  the 
  move- 
  

   ment 
  at 
  least 
  has 
  occurred 
  in 
  post-Claiborne 
  time. 
  

  

  The 
  Mud 
  Lumps 
  

  

  Description. 
  — 
  The 
  peculiar 
  upheavals 
  in 
  the 
  channel 
  and 
  around 
  

   the 
  mouths 
  of 
  the 
  Mississippi, 
  early 
  forced 
  themselves 
  on 
  the 
  notice 
  

   of 
  persons 
  interested 
  in 
  the 
  navigation 
  of 
  the 
  river. 
  Parts 
  of 
  the 
  

   bottom 
  of 
  the 
  river 
  gradually 
  elevate 
  themselves 
  until 
  dome- 
  

   shaped 
  masses 
  of 
  blue 
  clay 
  project 
  two 
  or 
  three 
  feet 
  above 
  the 
  

   surface 
  of 
  the 
  water. 
  Openings 
  are 
  formed 
  in 
  the 
  summits 
  of 
  

   these 
  cones, 
  from 
  which 
  water 
  and 
  mud 
  and 
  gas 
  issue. 
  The 
  

   mud 
  is 
  deposited 
  about 
  the 
  orifice 
  in 
  successive 
  layers 
  and 
  builds 
  

   up 
  a 
  miniature, 
  volcanic-like 
  cone. 
  This 
  process 
  continues 
  until 
  

   the 
  elevation 
  of 
  the 
  cones 
  sometimes 
  reaches 
  ten 
  or 
  even 
  twelve 
  

   feet. 
  The 
  eruption 
  then 
  entirely 
  ceases 
  or 
  an 
  opening 
  is 
  made 
  

   at 
  a 
  lower 
  level. 
  The 
  extinct 
  cones 
  are 
  finally 
  destroyed 
  by 
  the 
  

   waves. 
  

  

  Theories 
  of 
  origin. 
  — 
  Naturally 
  many 
  theories 
  have 
  been 
  

   proposed 
  to 
  account 
  for 
  the 
  origin 
  of 
  the 
  sepeculiar 
  eruptions 
  

   but 
  none 
  has 
  yet 
  been 
  advanced 
  which 
  has 
  received 
  the 
  

   undivided 
  support 
  of 
  scientists. 
  The 
  theories 
  may 
  be 
  enumer- 
  

   ated 
  as 
  follows 
  : 
  

  

  