﻿INTRUSIVE 
  HOCKS. 
  143 
  

  

  ordinary 
  detritus 
  filling- 
  the 
  bed 
  of 
  the 
  stream. 
  Close 
  to 
  the 
  block, 
  a 
  

   few 
  fragments 
  of 
  trachyte 
  are 
  seen 
  lying 
  1 
  , 
  which 
  have 
  scaled 
  off 
  from 
  it 
  

   from 
  atmospheric 
  action; 
  but 
  no 
  other 
  traces 
  of 
  the 
  presence 
  of 
  an 
  

   intrusive 
  rock 
  occur 
  in 
  the 
  neighbourhood. 
  One 
  small 
  fragment, 
  however, 
  

   I 
  noticed 
  of 
  pale 
  shale, 
  little 
  bigger 
  than 
  the 
  palm 
  of 
  my 
  hand, 
  which 
  

   was 
  somewhat 
  hardened 
  and 
  jaspery, 
  and 
  one 
  side 
  of 
  which 
  had 
  a 
  some- 
  

   what 
  baked 
  aspect, 
  as 
  though 
  it 
  might 
  have 
  formed 
  part 
  of 
  the 
  wall 
  

   of 
  a 
  dyke 
  ; 
  and 
  this, 
  I 
  believe, 
  is 
  the 
  key 
  to 
  the 
  curious 
  occurrence 
  of 
  an 
  

   isolated 
  mass 
  of 
  trachyte 
  in 
  the 
  midst 
  of 
  unaltered 
  Nummulitic 
  strata. 
  

  

  My 
  idea 
  is, 
  that 
  the 
  ' 
  Chouk 
  -talon' 
  is 
  the 
  remnant 
  of 
  a 
  pipe 
  of 
  

   trachyte, 
  or 
  the 
  stony 
  plug 
  filling 
  a 
  pipe-vein 
  up 
  which 
  a 
  trachytic 
  

   effusion 
  had 
  taken 
  place, 
  and 
  to 
  the 
  small 
  diameter 
  of 
  which, 
  the 
  little 
  

   disturbance 
  or 
  alteration 
  in 
  the 
  shales 
  traversed 
  by 
  it 
  is 
  due. 
  All 
  the 
  

   circumstances 
  considered, 
  I 
  know 
  of 
  no 
  other 
  alternative 
  to 
  the 
  expla- 
  

   nation 
  above 
  given, 
  nor 
  do 
  I 
  know 
  of 
  any 
  nearer 
  locality, 
  where 
  any 
  

   similar 
  rock 
  occurs, 
  than 
  Barren 
  Island, 
  in 
  the 
  Bay 
  of 
  Bengal 
  to 
  the 
  

   South, 
  with 
  which 
  focus 
  of 
  volcanic 
  activity 
  it 
  may 
  not 
  improbably 
  have 
  

   been 
  connected. 
  A 
  straight 
  line 
  from 
  Barren 
  Island 
  to 
  Puppa-doung, 
  

   the 
  former 
  an 
  active 
  volcano, 
  the 
  latter 
  at 
  present 
  in 
  a 
  sate 
  of 
  quies- 
  

   cence, 
  measures 
  614 
  miles. 
  At 
  100 
  miles 
  from 
  Barren 
  Island, 
  but 
  ten 
  

   miles 
  to 
  the 
  Eastward 
  of 
  that 
  line, 
  is 
  the 
  volcanic 
  mass 
  of 
  Narkondam 
  

   Island, 
  whilst 
  at 
  293 
  miles 
  from 
  Barren 
  Island 
  and 
  fifteen 
  miles 
  to 
  the 
  

   Eastward 
  of 
  the 
  same 
  line, 
  comes 
  in 
  the 
  above 
  mentioned 
  trachyte 
  

   plug 
  of 
  Chouk-talon, 
  being 
  almost 
  midway 
  to 
  Puppa 
  : 
  whence 
  I 
  think 
  

   we 
  may 
  conclude 
  that 
  Puppa 
  is 
  the 
  most 
  Northerly 
  known 
  point 
  of 
  

   that 
  volcanic 
  zone 
  to 
  which 
  Barren 
  Island 
  pertains. 
  

  

  Serpentine. 
  — 
  In 
  Pegu, 
  serpentine 
  occurs 
  in 
  three 
  distinct 
  localities, 
  or 
  

   localised 
  areas, 
  all 
  situated 
  on 
  the 
  Eastern 
  side 
  of 
  the 
  Arakan 
  range 
  and 
  

   among 
  the 
  outer 
  ranges 
  of 
  hills. 
  The 
  only 
  exception 
  to 
  this 
  rule 
  known 
  

   to 
  me 
  is 
  the 
  occurrence 
  of 
  serpentine 
  in 
  minute 
  quantity 
  on 
  the 
  North 
  of 
  

   Shuaydoung, 
  and 
  more 
  plentifully 
  on 
  its 
  Southern 
  flanks 
  close 
  to 
  the 
  

  

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