﻿GEOLOGICAL 
  STRUCTURE 
  OF 
  THE 
  HEKRAN 
  COAST. 
  53 
  

  

  ebullition 
  and 
  discharge) 
  is 
  much 
  increased 
  at 
  spring 
  tides 
  ; 
  and 
  this 
  

   the 
  writer 
  has 
  heard 
  from 
  several 
  different 
  sources. 
  

  

  None 
  have 
  been 
  heard 
  of 
  more 
  than 
  a 
  few 
  miles 
  from 
  the 
  shore, 
  so 
  

   far 
  as 
  the 
  writer 
  is 
  aware. 
  

  

  As 
  to 
  the 
  causes 
  of 
  the 
  present 
  configuration 
  of 
  the 
  coast, 
  it 
  is 
  

   suggested 
  that 
  since 
  the 
  deposit 
  of 
  the 
  Miocene 
  beds 
  the 
  great 
  sub- 
  

   marine 
  cliff 
  may 
  at 
  one 
  period 
  have 
  been 
  raised 
  above 
  the 
  sea, 
  

   which 
  then 
  washed 
  its 
  base 
  — 
  that 
  the 
  coast 
  then 
  subsided, 
  probably 
  

   to 
  near 
  the 
  present 
  level, 
  when 
  the 
  beds 
  were 
  removed 
  from 
  the 
  

   edge 
  of 
  the 
  great 
  cliff 
  to 
  the 
  present 
  coast-line 
  — 
  and 
  that 
  the 
  coast 
  

   may 
  have 
  been 
  depressed 
  below 
  its 
  present 
  level 
  sufficiently 
  to 
  allow 
  

   the 
  sea 
  to 
  produce 
  the 
  present 
  inland 
  cliffs, 
  since 
  which 
  it 
  has 
  been 
  

   again 
  slightly 
  raised. 
  

  

  The 
  presence 
  of 
  Lithodomus 
  in 
  the 
  clay 
  considerably 
  above 
  the 
  

   present 
  sea-level 
  seems 
  to 
  warrant, 
  at 
  any 
  rate, 
  the 
  latter 
  hypothesis. 
  

  

  The 
  author's 
  time 
  when 
  visiting 
  the 
  places 
  on 
  the 
  coast 
  has 
  been 
  

   much 
  taken 
  up 
  with 
  his 
  duties 
  connected 
  with 
  the 
  telegraph 
  cable, 
  

   which 
  is 
  his 
  excuse 
  for 
  the 
  incompleteness 
  of 
  the 
  information 
  and 
  of 
  

   the 
  series 
  of 
  fossils. 
  

  

  Discussion. 
  

  

  Mr. 
  Evans 
  thought 
  that 
  the 
  fact 
  of 
  the 
  mud 
  from 
  some 
  of 
  the 
  

   cones 
  having 
  ceased 
  to 
  flow 
  was 
  in 
  favour 
  of 
  the 
  theory 
  of 
  their 
  

   being 
  due 
  to 
  hydrostatic 
  action, 
  the 
  outflow 
  ceasing 
  when 
  the 
  pres- 
  

   sure 
  was 
  insufficient 
  to 
  overcome 
  the 
  resistance, 
  and 
  a 
  fresh 
  vent 
  

   being 
  found 
  elsewhere. 
  

  

  Mr. 
  Forbes 
  had 
  frequently 
  observed 
  the 
  mud-craters 
  of 
  Peru, 
  

   which 
  were 
  undoubtedly 
  due 
  to 
  volcanic 
  action, 
  though 
  in 
  many 
  

   instances 
  the 
  outflow 
  was 
  cold, 
  or 
  nearly 
  so. 
  In 
  the 
  cases 
  described 
  

   by 
  the 
  author, 
  however, 
  it 
  was 
  possible 
  that 
  they 
  might 
  be 
  due 
  to 
  

   another 
  cause. 
  

  

  Prof. 
  PnrLLirs 
  mentioned 
  a 
  spring 
  which 
  rose 
  through 
  mud 
  in 
  

   Bridlington 
  Harbour, 
  from 
  which 
  the 
  outflow 
  varied 
  both 
  with 
  tide 
  

   and 
  rain. 
  The 
  spring 
  tides 
  in 
  the 
  Persian 
  Gulf 
  might 
  effect 
  a 
  rise 
  

   in 
  the 
  mud- 
  craters 
  by 
  obstructing 
  some 
  passage 
  by 
  which 
  water 
  from 
  

   the 
  upland 
  was 
  discharged 
  into 
  the 
  sea. 
  Were 
  this 
  so, 
  the 
  upward 
  

   movement 
  in 
  the 
  crater 
  would 
  on 
  each 
  occasion 
  probably 
  occur 
  some- 
  

   what 
  later 
  than 
  the 
  high 
  tides. 
  

  

  Mr. 
  Seeley 
  remarked 
  on 
  the 
  presence 
  of 
  undoubted 
  volcanic 
  action 
  

   in 
  the 
  district, 
  in 
  the 
  shape 
  of 
  hot 
  springs 
  (fee, 
  and 
  therefore 
  ques- 
  

   tioned 
  the 
  propriety 
  of 
  bringing 
  in 
  hydrostatic 
  pressure 
  to 
  account 
  

   for 
  the 
  phenomena. 
  

  

  Mr. 
  Miller 
  cited 
  the 
  mud-volcanoes 
  of 
  Iceland 
  as 
  instances 
  of 
  

   pure 
  volcanic 
  action, 
  and 
  drew 
  a 
  distinction 
  between 
  the 
  occurrence 
  

   of 
  mud- 
  craters 
  near 
  the 
  sea 
  and 
  at 
  a 
  distance 
  from 
  it. 
  

  

  The 
  Author, 
  in 
  reply, 
  observed 
  that 
  he 
  had 
  merely 
  suggested 
  the 
  

   possibility 
  of 
  the 
  outflow 
  being 
  due 
  to 
  hydrostatic 
  pressure, 
  and 
  did 
  

   not 
  insist 
  upon 
  it. 
  He 
  stated 
  that 
  there 
  was 
  ample 
  evidence 
  of 
  vol- 
  

   canic 
  action 
  at 
  a 
  distance 
  of 
  200 
  or 
  300 
  miles 
  from 
  the 
  district 
  he 
  

   had 
  described. 
  

  

  