﻿Jaggar 
  — 
  Lava 
  Flow 
  from 
  Mauna 
  Loa, 
  1916. 
  281 
  

  

  the 
  other 
  hand, 
  wherever 
  the 
  writer 
  saw 
  it, 
  was 
  always 
  strongly 
  

   oxidized 
  and 
  tarnished 
  to 
  various 
  colors 
  from 
  the 
  time 
  of 
  its 
  

   first 
  consolidation. 
  This 
  appeared 
  inevitable 
  from 
  the 
  manner 
  

   of 
  its 
  shrinkage 
  into 
  almost 
  endlessly 
  divisible 
  blocks 
  as 
  it 
  cooled 
  

   with 
  flames 
  playing 
  through 
  the 
  interstices 
  (fig. 
  7), 
  the 
  whole 
  

   process 
  appearing 
  to 
  be 
  a 
  consolidation 
  throughout 
  the 
  mass, 
  

   intimately 
  bound 
  up 
  with 
  gas 
  action, 
  in 
  contrast 
  to 
  the 
  skinning 
  

   and 
  crusting 
  over 
  with 
  a 
  definite 
  dermal 
  layer 
  which 
  is 
  the 
  dis- 
  

   tinguishing 
  feature 
  of 
  pahoehoe. 
  This 
  outer 
  layer 
  appears 
  to 
  

   confine 
  the 
  melt 
  by 
  forming 
  a 
  relatively 
  non-conducting 
  enve- 
  

   lope 
  and 
  the 
  consolidation 
  is 
  gradual 
  from 
  without 
  inwards, 
  

   the 
  magma 
  being 
  compelled 
  to 
  stretch, 
  crack, 
  break 
  through 
  

   or 
  push 
  from 
  under 
  the 
  outer 
  membrane, 
  which 
  in 
  turn 
  con- 
  

   fines 
  the 
  heat 
  and 
  preserves 
  an 
  inner 
  filament 
  in 
  a 
  liquid 
  con- 
  

   dition. 
  

  

  The 
  stages 
  of 
  consolidation 
  of 
  aa 
  as 
  described 
  in 
  these 
  flows 
  

   by 
  different 
  writers 
  it 
  is 
  of 
  some 
  interest 
  to 
  compare. 
  The 
  

   present 
  writer's 
  observations 
  on 
  May 
  24 
  of 
  liquid 
  aa 
  in 
  rapid 
  

   motion 
  are 
  quoted 
  above 
  in 
  the 
  journal. 
  In 
  that 
  same 
  Kahuku 
  

   district 
  two 
  nights 
  earlier 
  Mr. 
  Thornton 
  Hardy 
  saw 
  a 
  flow 
  

   rapidly 
  cool 
  down 
  and 
  he 
  has 
  kindly 
  furnished 
  me 
  with 
  the 
  

   following 
  description 
  : 
  

  

  " 
  The 
  flow 
  Mr. 
  Waldron 
  and 
  I 
  had 
  under 
  observation 
  was 
  the 
  

   toe 
  of 
  the 
  Kahuku 
  flow, 
  which 
  we 
  reached 
  at 
  dusk 
  or. 
  the 
  even- 
  

   ing 
  of 
  May 
  22. 
  When 
  we 
  first 
  saw 
  it 
  the 
  point 
  was 
  descending 
  

   rather 
  steeply 
  into 
  a 
  gully 
  leading 
  down 
  into 
  the 
  koa 
  forest 
  just 
  

   below. 
  Shrubs, 
  bushes 
  and 
  stunted 
  trees 
  stood 
  in 
  its 
  path, 
  and 
  

   these, 
  from 
  time 
  to 
  time, 
  it 
  battered 
  down 
  and 
  buried 
  with 
  small 
  

   avalanches 
  of 
  loose 
  slabs, 
  or 
  grubbed 
  up 
  and 
  pushed 
  ahead 
  of 
  it, 
  

   flaming 
  brightly. 
  The 
  movement 
  was 
  very 
  slow, 
  only 
  a 
  few 
  feet 
  

   an 
  hour, 
  and 
  later 
  became 
  almost 
  imperceptible. 
  From 
  the 
  first, 
  

   it 
  was 
  to 
  be 
  measured 
  only 
  by 
  its 
  advance 
  on 
  some 
  fixed 
  land- 
  

   mark, 
  such 
  as 
  a 
  doomed 
  tree. 
  

  

  Our 
  first 
  intimation 
  of 
  proximity 
  was 
  the 
  great 
  shimmering 
  

   billows 
  of 
  heat 
  we 
  saw 
  rising 
  ahead 
  of 
  us, 
  as 
  far 
  upward 
  as 
  the 
  

   eye 
  could 
  reach, 
  drifting 
  down 
  the 
  w 
  r 
  ind 
  and 
  troubling 
  the 
  dying 
  

   light 
  of 
  day. 
  Next, 
  we 
  heard 
  the 
  crunching, 
  crackling, 
  tumbling, 
  

   crashing 
  noise 
  of 
  the 
  march 
  itself. 
  At 
  that 
  point, 
  the 
  tiptoe 
  of 
  

   the 
  column, 
  much 
  restricted 
  from 
  its 
  width 
  above, 
  was 
  perhaps 
  

   fifty 
  feet 
  (15 
  m.) 
  across, 
  and, 
  sloping 
  steeply 
  backward, 
  thirty 
  

   feet 
  (9 
  m.) 
  in 
  depth. 
  There 
  was 
  no 
  sound 
  of 
  gushing 
  or 
  hissing, 
  

   though 
  here 
  and 
  there, 
  at 
  wide 
  intervals, 
  jets 
  of 
  gas 
  burned 
  with 
  

   a 
  silent 
  blue 
  flame, 
  barely 
  luminous 
  : 
  and 
  there 
  was 
  almost 
  no 
  

   odor. 
  What 
  little 
  there 
  was 
  smelt 
  like 
  the 
  fume 
  of 
  an 
  anthracite 
  

   fire. 
  The 
  surface 
  of 
  this 
  massive 
  wedge 
  — 
  for 
  such 
  it 
  seemed, 
  rather 
  

   than 
  a 
  river, 
  a 
  flow, 
  or 
  any 
  of 
  the 
  other 
  conventional 
  epithets 
  

   applied 
  — 
  was 
  incredibly 
  rough 
  and 
  rugged 
  in 
  texture 
  and 
  dull 
  

   black 
  in 
  color. 
  More 
  than 
  anything 
  else 
  it 
  resembled 
  a 
  glacial 
  

  

  