﻿BARREN 
  ISLAND. 
  II 
  

  

  cent, 
  of 
  silica. 
  Three 
  compact 
  specimens 
  were 
  found 
  to 
  have 
  specific 
  

   gravities 
  of 
  2*77, 
  2*80, 
  and 
  2*87. 
  Most 
  of 
  those 
  submitted 
  to 
  examin- 
  

   ation 
  may, 
  I 
  think, 
  be 
  correctly 
  designated 
  ( 
  doleritic 
  lava/ 
  while 
  some 
  

   verge 
  towards 
  anamesite. 
  

  

  The 
  fragmentary 
  e 
  jecta 
  which 
  are 
  interstratified 
  with 
  the 
  lavas 
  of 
  the 
  

  

  Fragmentary 
  ejecta 
  of 
  ancient 
  cone 
  are 
  exposed 
  in 
  some 
  few 
  good 
  sections 
  

   the 
  ancient 
  cone. 
  a 
  i 
  ong 
  . 
  t 
  \ 
  w 
  coast# 
  ^t 
  the 
  mouth 
  of 
  the 
  water-course 
  

  

  which 
  runs 
  into 
  the 
  sea 
  300 
  yards 
  south-west 
  of 
  the 
  most 
  northerly 
  point 
  

   of 
  the 
  island 
  there 
  is 
  a 
  cliff, 
  some 
  60 
  or 
  80 
  feet 
  high, 
  composed 
  of 
  ancient 
  

   scoriae 
  of 
  a 
  dull 
  red 
  colour. 
  In 
  more 
  than 
  one 
  place 
  on 
  the 
  face 
  of 
  the 
  

   cliff 
  the 
  irregular 
  stratification 
  of 
  the 
  scoria? 
  shows 
  unconformity, 
  where 
  

   layers 
  have 
  been 
  cut 
  away 
  by 
  denudation, 
  and 
  others 
  subsequently 
  depos- 
  

   ited 
  with 
  a 
  different 
  inclination. 
  A 
  little 
  further 
  east 
  similar 
  scoriae 
  

   are 
  rudely 
  interbedded 
  with 
  irregular 
  layers 
  of 
  lava, 
  some 
  of 
  which 
  are 
  

   not 
  more 
  than 
  a 
  few 
  inches 
  thick. 
  One 
  hundred 
  yards 
  north-west 
  of 
  the 
  

   landing-place 
  a 
  somewhat 
  contorted 
  bed 
  of 
  black 
  volcanic 
  ash 
  is 
  inter- 
  

   stratified 
  with 
  a 
  similar 
  alternation 
  of 
  scoria? 
  and 
  lava. 
  Some 
  of 
  the 
  

   layers 
  of 
  ash 
  resist 
  the 
  weather 
  better 
  than 
  others, 
  and 
  stand 
  out 
  in 
  relief, 
  

   thus 
  clearly 
  indicating 
  the 
  miniature 
  faults, 
  of 
  a 
  few 
  inches 
  throw, 
  by 
  

   which 
  the 
  bed 
  has 
  been 
  dislocated. 
  Along 
  the 
  fault-lines, 
  again, 
  the 
  ash 
  

   has 
  been 
  hardened 
  (probably 
  by 
  infiltration), 
  and 
  the 
  faults 
  are, 
  therefore, 
  

   marked 
  by 
  lines 
  in 
  relief. 
  Another 
  interesting 
  section 
  is 
  well 
  exposed 
  

   in 
  the 
  little 
  bay 
  about 
  half 
  a 
  mile 
  south 
  of 
  the 
  landing-place, 
  showing 
  

   perhaps 
  50 
  feet 
  of 
  agglomerate, 
  composed 
  of 
  ash, 
  scoria?, 
  and 
  ejected 
  

   blocks 
  of 
  lava 
  up 
  to 
  3 
  or 
  4 
  feet 
  in 
  diameter. 
  Besides 
  lumps 
  of 
  the 
  ordi- 
  

   nary 
  lavas, 
  as 
  described 
  above, 
  there 
  are 
  some 
  of 
  greenish, 
  nearly 
  black, 
  

   basalt, 
  containing 
  granules 
  of 
  olivine, 
  and 
  breaking 
  with 
  sub-conchoidal 
  

   fracture 
  — 
  the 
  only 
  true 
  basalt 
  that 
  I 
  have 
  observed 
  on 
  the 
  island. 
  Near 
  

   the 
  middle 
  of 
  the 
  heterogeneous 
  mass 
  of 
  materials 
  there 
  is 
  a 
  bed 
  of 
  fine, 
  

   homogeneous 
  ash. 
  

  

  On 
  the 
  face 
  of 
  the 
  cliff 
  close 
  to 
  the 
  landing-place, 
  a 
  stream 
  of 
  ancient 
  

  

  Ancient 
  aqueous 
  (?) 
  lava 
  overlies 
  a 
  volcanic 
  agglomerate, 
  the 
  great 
  

   deposits. 
  majority 
  of 
  the 
  pebbles 
  and 
  lumps 
  in 
  which 
  are 
  

  

  more 
  or 
  less 
  rounded. 
  They 
  are 
  embedded 
  in 
  a 
  sandy, 
  or 
  even 
  clayey, 
  

   matrix, 
  and 
  in 
  the 
  midst 
  of 
  the 
  agglomerate 
  is 
  a 
  stratum 
  of 
  sandy 
  clay 
  

  

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