﻿BARREN 
  ISLAND. 
  9 
  

  

  towards 
  Port 
  Blair. 
  None 
  of 
  these 
  touched 
  bottom 
  at 
  200 
  to 
  680 
  

   fathoms; 
  the 
  last-mentioned 
  is 
  37 
  miles 
  south-west 
  of 
  the 
  volcano 
  and 
  

   only 
  1 
  5 
  from 
  the 
  nearest 
  of 
  the 
  Andaman 
  group. 
  Towards 
  the 
  east 
  the 
  

   nearest 
  sounding 
  recorded 
  is 
  100 
  miles 
  from 
  Barren 
  Island, 
  and 
  that 
  

   is 
  1,260 
  fathoms, 
  with 
  no 
  bottom. 
  

  

  From 
  two 
  to 
  four 
  hundred 
  yards 
  southward 
  and 
  south-eastward 
  of 
  the 
  

  

  great 
  crater 
  rim, 
  there 
  is 
  a 
  second, 
  and 
  rudely 
  

   Denudation 
  ridge. 
  . 
  . 
  J 
  

  

  concentric, 
  ridge, 
  which 
  bears 
  some 
  little 
  re- 
  

   semblance 
  to 
  the 
  edge 
  of 
  a 
  still 
  older 
  and 
  larger 
  crater. 
  But 
  it 
  is 
  

   clearly 
  due 
  to 
  denudation 
  only, 
  and 
  the 
  water-shed 
  joining 
  the 
  two 
  ridges 
  

   is 
  almost 
  level. 
  Where 
  rocks 
  having 
  unequal 
  powers 
  of 
  resisting 
  

   erosion, 
  like 
  lava 
  and 
  scoriae, 
  occur 
  in 
  alternating 
  masses, 
  the 
  natural 
  

   tendency, 
  of 
  course, 
  is 
  for 
  pluvial 
  denudation 
  to 
  scoop 
  out 
  the 
  softer 
  into 
  

   valleys 
  parallel 
  to 
  the 
  outcrop. 
  

  

  The 
  ancient 
  cone 
  of 
  Barren 
  Island, 
  is, 
  as 
  I 
  have 
  already 
  indicated, 
  

   Lavas 
  of 
  the 
  ancient 
  largely 
  made 
  up 
  of 
  lava, 
  although 
  perhaps 
  not 
  

   cone 
  - 
  to 
  such 
  an 
  extent 
  as 
  might 
  appear 
  at 
  first 
  sight- 
  

  

  Loosely 
  coherent 
  materials, 
  like 
  agglomerate 
  and 
  scoriae, 
  are 
  ill- 
  calcu- 
  

   lated 
  to 
  withstand 
  the 
  wear 
  of 
  the 
  sea, 
  which 
  tends 
  to 
  eat 
  them 
  back 
  

   until 
  it 
  meets 
  with 
  some 
  more 
  solid 
  rock. 
  Hence 
  one 
  sees 
  comparatively 
  

   little 
  of 
  the 
  fragmentary 
  ejecta 
  in 
  pulling 
  round 
  the 
  island, 
  although 
  

   good 
  sections 
  are 
  to 
  be 
  found 
  in 
  a 
  few 
  partially 
  sheltered 
  spots. 
  The 
  

   lava 
  streams 
  exposed 
  in 
  section 
  along 
  the 
  coast 
  show 
  the 
  usual 
  scoriaceous 
  

   layer 
  at 
  the 
  bottom 
  of 
  the 
  flow, 
  which 
  is 
  apt 
  to 
  get 
  hollowed 
  out 
  by 
  

   the 
  waves, 
  until 
  a 
  cave 
  is 
  formed 
  of 
  which 
  the 
  more 
  solid 
  lava 
  forms 
  the 
  

   roof. 
  Eventually 
  the 
  roof 
  falls 
  in, 
  filling 
  the 
  cave 
  with 
  a 
  confused 
  mass 
  

   of 
  loose 
  blocks. 
  

  

  Dykes, 
  so 
  numerous 
  in 
  some 
  volcanoes, 
  are 
  not 
  met 
  with 
  very 
  frequently 
  

   at 
  Barren 
  Island. 
  Close 
  to 
  the 
  landing-place 
  1 
  one 
  may 
  be 
  seen, 
  which 
  is 
  

   vertical, 
  running 
  east 
  and 
  west, 
  or 
  nearly 
  radially 
  to 
  the 
  volcano 
  : 
  it 
  is 
  

   about 
  6 
  or 
  7 
  feet 
  thick, 
  and 
  composed 
  of 
  lava 
  very 
  similar 
  to 
  that 
  it 
  

   penetrates. 
  

  

  1 
  At 
  the 
  hot 
  spring. 
  

  

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