﻿Haast. 
  — 
  On 
  the 
  Geological 
  Structure 
  of 
  Banks 
  Peninsula. 
  609 
  

  

  inner 
  slope 
  by 
  stony 
  lava-streams, 
  consolidated 
  during 
  tlieir 
  ascent. 
  Or, 
  

   to 
  offer 
  another 
  explanation, 
  we 
  might 
  regard 
  these 
  two 
  stony 
  lava-streams, 
  

   233 
  and 
  237, 
  as 
  having 
  broken 
  through 
  the 
  huge 
  accumulations 
  of 
  ejecta 
  

   which 
  were 
  heaped 
  up 
  all 
  round 
  the 
  crater's 
  mouth-^a 
  phenomenon 
  

   frequently 
  observed 
  during 
  violent 
  volcanic 
  eruptions, 
  when 
  a 
  huge 
  cinder 
  

   cone 
  is 
  formed 
  in 
  a 
  short 
  time. 
  A 
  similar 
  occurrence 
  seems 
  to 
  have 
  taken 
  

   place 
  more 
  towards 
  the 
  centre 
  of 
  the 
  tunnel, 
  about 
  60 
  chains 
  from 
  the 
  

   Lyttelton 
  side, 
  where 
  a 
  large 
  stony 
  lava-stream, 
  No. 
  167, 
  is 
  seen 
  to 
  ascend 
  

   through 
  the 
  agglomerate 
  bed 
  or 
  beds, 
  Nos. 
  166 
  to 
  168. 
  The 
  lava-stream, 
  

   163, 
  in 
  close 
  proximity, 
  might 
  be 
  considered 
  to 
  be 
  the 
  continuation 
  of 
  the 
  

   former, 
  which 
  here 
  flows 
  doAvn 
  the 
  steep 
  side 
  of 
  the 
  cinder 
  cone. 
  Gradually, 
  

   as 
  we 
  retreat 
  from 
  the 
  focus 
  of 
  eruption, 
  the 
  agglomerate 
  beds 
  decrease 
  in 
  

   number 
  and 
  size, 
  but 
  they 
  still 
  are 
  occasionally 
  present 
  even 
  close 
  to 
  the 
  

   mouth 
  of 
  the 
  tunnel 
  near 
  to 
  the 
  Heathcote 
  entrance. 
  Some 
  of 
  them 
  con- 
  

   sist 
  in 
  their 
  lower 
  portion 
  of 
  fine 
  ashes, 
  or 
  lava 
  d'aqua, 
  and 
  above 
  of 
  scori® 
  

   and 
  lapilli, 
  so 
  as 
  to 
  suggest 
  that 
  first 
  fine 
  ashes 
  had 
  been 
  thrown 
  out 
  or 
  

   had 
  been 
  brought 
  down 
  the 
  side 
  in 
  the 
  form 
  of 
  a 
  mud 
  stream, 
  on 
  the 
  top 
  

   of 
  which 
  large 
  ejecta 
  were 
  afterwards 
  deposited. 
  Another 
  agglomerate 
  bed 
  

   having 
  an 
  anticlinal 
  or 
  saddle 
  arrangement 
  is 
  22a, 
  17 
  to 
  20 
  chains 
  from 
  the 
  

   Lyttelton 
  end; 
  it 
  was 
  evidently 
  deposited 
  on 
  the 
  rim 
  of 
  the 
  crater, 
  of 
  

   which 
  the 
  uneven 
  surface 
  is 
  well 
  visible 
  in 
  its 
  lower 
  portion. 
  After 
  its 
  

   formation, 
  two 
  more 
  agglomerate 
  beds 
  were 
  deposited 
  over 
  it, 
  216 
  and 
  227, 
  

   and 
  211 
  and 
  228 
  in 
  the 
  section, 
  each 
  being 
  separated 
  from 
  the. 
  other 
  by 
  a 
  

   bed 
  of 
  laterite. 
  Moreover, 
  it 
  is 
  clear 
  that, 
  whatever 
  may 
  have 
  been 
  its 
  origin, 
  

   the 
  lowest 
  portion 
  of 
  this 
  and 
  several 
  other 
  agglomerate 
  beds 
  must 
  have 
  

   been 
  deposited 
  when 
  in 
  a 
  state 
  of 
  high 
  temperature, 
  as 
  the 
  argillaceous 
  bed 
  

   below 
  it 
  has 
  been 
  burnt 
  red, 
  so 
  as 
  to 
  take 
  all 
  the 
  characteristics 
  of 
  a 
  laterite. 
  

   All 
  round 
  Banks 
  Peninsula 
  agglomerate 
  and 
  ash 
  beds 
  are 
  visible 
  in 
  the 
  

   cliffs, 
  but 
  they 
  are 
  Hke 
  the 
  lava-streams 
  of 
  small 
  vertical 
  extent 
  only, 
  and 
  

   we 
  have 
  to 
  approach 
  more 
  towards 
  the 
  centre 
  of 
  eruption 
  when 
  we 
  wish 
  

   to 
  see 
  them 
  in 
  their 
  greatest 
  dimensions. 
  

  

  The 
  largest 
  and 
  most 
  numerous 
  stony 
  lava-streams 
  are 
  met 
  with 
  towards 
  

   the 
  centre 
  of 
  the 
  tunnel, 
  where 
  the 
  basalt 
  of 
  which 
  they 
  are 
  composed 
  

   possesses 
  the 
  greatest 
  hardness 
  and 
  crystalline 
  texture. 
  More 
  towards 
  the 
  

   boundaries 
  of 
  the 
  volcanic 
  system, 
  the 
  lava-streams 
  are 
  much 
  thinner 
  and 
  

   at 
  the 
  same 
  time 
  more 
  porphyritic, 
  amygdaloidal 
  or 
  scoriaceous, 
  and 
  it 
  is 
  

   very 
  instructive 
  to 
  follow 
  some 
  of 
  the 
  lava-streams 
  which 
  form 
  clear 
  sections 
  

   in 
  the 
  deep 
  valleys 
  radiating 
  round 
  the 
  peninsula, 
  from 
  the 
  summit 
  of 
  the 
  

   caldera 
  wall 
  to 
  their 
  termination 
  at 
  its 
  foot, 
  and 
  to 
  note 
  the 
  gradual 
  change 
  

   in 
  their 
  size, 
  and 
  in 
  the 
  texture 
  of 
  the 
  rocks 
  of 
  which 
  they 
  are 
  composed. 
  I 
  

   have 
  already 
  alluded 
  to 
  the 
  lava-stream 
  237, 
  nine 
  chains 
  from 
  the 
  Lyttelton 
  

  

  