﻿52 
  A. 
  W. 
  STIFFE 
  ON 
  THE 
  MUD- 
  CRATERS 
  AND 
  

  

  in 
  height 
  from 
  20 
  to 
  300 
  or 
  400 
  feet 
  above 
  the 
  plain 
  ; 
  and 
  a 
  probable 
  

   section 
  is 
  shown 
  in 
  the 
  diagram 
  (fig; 
  3). 
  They 
  rise 
  out 
  of 
  the 
  clay- 
  

   plain 
  many 
  miles 
  from 
  any 
  hills, 
  and 
  are 
  cones 
  of 
  clay 
  of 
  very 
  regular 
  

   form, 
  with 
  truncated 
  tops, 
  and 
  sides 
  at 
  an 
  angle^estimated 
  at 
  about 
  40°, 
  

   or 
  whatever 
  the 
  limiting 
  angle 
  or 
  angle 
  of 
  rest 
  of 
  such 
  mud 
  may 
  be. 
  

  

  The 
  largest 
  one 
  ascended 
  by 
  the 
  writer 
  was 
  about 
  100 
  feet 
  

   wide 
  on 
  top, 
  and 
  nearly 
  circular 
  ; 
  it 
  resembled 
  a 
  cup 
  filled 
  to 
  the 
  

   brim 
  with 
  semiliquid 
  mud 
  somewhat 
  thicker 
  than 
  treacle, 
  which 
  

   slowly 
  and 
  only 
  now 
  and 
  again 
  overflowed, 
  trickling 
  down 
  the 
  outside 
  

   of 
  the 
  cone, 
  but 
  scarcely 
  sufficient 
  in 
  quantity 
  to 
  reach 
  the 
  base. 
  

   From 
  time 
  to 
  time 
  an 
  ebullition 
  of 
  gas 
  or 
  air 
  took 
  place 
  from 
  the 
  

   surface 
  of 
  the 
  pool. 
  

  

  Mr. 
  "Ward 
  has 
  kindly 
  analyzed 
  the 
  mud 
  ejected, 
  and 
  found 
  it 
  to 
  

   consist 
  chiefly 
  of 
  clay 
  with 
  a 
  large 
  admixture 
  of 
  carbonate 
  of 
  lime 
  

   and 
  a 
  small 
  proportion 
  of 
  quartz 
  sand. 
  The 
  aqueous 
  part 
  contains 
  

   much 
  chlorine, 
  a 
  little 
  sulphuric 
  acid, 
  a 
  little 
  lime, 
  with 
  soda 
  and 
  

   a 
  trace 
  of 
  potash. 
  No 
  magnesia 
  was 
  detected 
  in 
  the 
  solution. 
  It 
  

   would 
  therefore 
  probably 
  be 
  merely 
  a 
  water 
  containing 
  common 
  

   salt 
  with 
  a 
  little 
  sulphate 
  of 
  lime. 
  

  

  The 
  edge 
  or 
  lip 
  of 
  the 
  cup 
  was 
  very 
  narrow, 
  in 
  parts 
  barely 
  

   allowing 
  room 
  to 
  walk 
  round 
  it, 
  and 
  being 
  quite 
  soft 
  under 
  foot. 
  A 
  

   plummet 
  on 
  being 
  thrown 
  in 
  from 
  the 
  side 
  sank 
  rapidly 
  from 
  50 
  to 
  60 
  

   feet, 
  when 
  it 
  stopped, 
  apparently 
  from 
  the 
  friction 
  of 
  the 
  line 
  

   against 
  the 
  side, 
  there 
  being 
  no 
  means 
  at 
  hand 
  of 
  lowering 
  it 
  over 
  

   the 
  centre. 
  There 
  is 
  no 
  heat 
  accompanying 
  the 
  phenomenon 
  ; 
  and 
  

   there 
  is 
  no 
  reasonable 
  doubt 
  that 
  the 
  walls 
  of 
  the 
  cones 
  are 
  formed 
  

   entirely 
  by 
  the 
  accumulated 
  overflow 
  and 
  induration 
  of 
  mud. 
  

  

  It 
  is 
  therefore 
  a 
  question 
  whether 
  it 
  is 
  necessary 
  to 
  resort 
  to 
  vol- 
  

   • 
  canic 
  agency, 
  or 
  whether 
  hydrostatic 
  pressure 
  alone 
  is 
  not 
  quite 
  

   sufficient 
  to 
  account 
  for 
  these 
  mud-springs, 
  as 
  they 
  may 
  perhaps 
  be 
  

   more 
  appropriately 
  called. 
  

  

  The 
  thickness 
  of 
  the 
  clay 
  deposit 
  below 
  the 
  level 
  of 
  the 
  plains 
  is 
  

   unknown 
  ; 
  the 
  veins 
  of 
  gypsum 
  seem 
  to 
  indicate 
  it 
  is 
  not 
  merely 
  

   superficial, 
  or 
  derived 
  fram 
  the 
  denudation 
  of 
  the 
  hills. 
  Prom 
  the 
  

   form 
  of 
  the 
  sea- 
  bottom 
  it 
  is 
  possible 
  that 
  the 
  same 
  clay 
  beds 
  which 
  

   form 
  the 
  hills 
  attain 
  a 
  considerable 
  thickness 
  below 
  the 
  present 
  sea- 
  

   level. 
  The 
  sea-bottom 
  for 
  some 
  miles 
  from 
  the 
  coast 
  is 
  of 
  similar 
  

   nature 
  and 
  appearance 
  to 
  the 
  clay 
  of 
  the 
  plains, 
  with 
  a 
  depth 
  of 
  water 
  

   increasing 
  gradually 
  to 
  20 
  or 
  30 
  fathoms 
  and 
  then 
  sinking 
  suddenly 
  

   and 
  (in 
  several 
  places, 
  at 
  least) 
  quite 
  precipitously 
  to 
  a 
  depth 
  of 
  from 
  

   300 
  to 
  400 
  fathoms. 
  

  

  There 
  is 
  some 
  evidence 
  of 
  the 
  existence 
  of 
  these 
  curious 
  craters 
  

   under 
  the 
  sea. 
  Near 
  Jashak 
  I 
  discovered 
  a 
  shoal, 
  three 
  miles 
  off 
  

   shore, 
  rising 
  suddenly 
  from 
  13 
  fathoms 
  to 
  a 
  height 
  of 
  only 
  10 
  feet 
  

   below 
  the 
  surface. 
  It 
  is 
  very 
  small, 
  not 
  a 
  ship's 
  length 
  across, 
  and 
  

   composed 
  of 
  clay 
  which, 
  on 
  the 
  shoal 
  part, 
  was 
  so 
  tenacious 
  that 
  the 
  

   lead 
  could 
  hardly 
  be 
  disengaged 
  when 
  let 
  go 
  on 
  it. 
  It 
  is 
  unusual 
  

   to 
  find 
  so 
  small 
  a 
  shoal 
  unless 
  of 
  rock 
  ; 
  and 
  it 
  is 
  suggested 
  that 
  it 
  may 
  

   be 
  probably 
  of 
  similar 
  origin 
  to 
  the 
  craters 
  on 
  shore. 
  

  

  The 
  natives 
  state 
  that 
  the 
  action 
  of 
  these 
  craters 
  (the 
  amount 
  of 
  

  

  