﻿AND 
  BANDED 
  CRYSTALLINE 
  ROCKS 
  OE 
  THE 
  LIZARD. 
  527 
  

  

  beginning 
  of 
  which 
  is 
  seen 
  at 
  /. 
  At 
  g 
  a 
  second 
  more 
  imperfectly 
  

   marked 
  stream 
  is 
  seen 
  flowing 
  from 
  e 
  to 
  /. 
  The 
  presence 
  of 
  

  

  Fig. 
  4. 
  — 
  Serpentinous 
  Streams. 
  

  

  % 
  % 
  jy 
  

  

  

  chlorite, 
  calcite, 
  limonite, 
  analcime, 
  and 
  epidote 
  (which 
  usually 
  con- 
  

   tains 
  over 
  2 
  per 
  cent, 
  of 
  water 
  * 
  in 
  its 
  composition) 
  affords 
  presump- 
  

   tive 
  evidence 
  of 
  the 
  action 
  of 
  water 
  ; 
  for 
  these 
  minerals 
  are 
  commonly 
  

   found 
  in 
  the 
  amygdules 
  of 
  lavas 
  ; 
  and 
  it 
  is 
  worth 
  mentioning 
  that 
  

   some 
  cracks 
  in 
  the 
  rocks 
  under 
  description 
  in 
  this 
  paper 
  contain 
  horn- 
  

   blende, 
  plagioclase, 
  and 
  sphene, 
  from 
  which 
  I 
  infer 
  that 
  they 
  also 
  

   may 
  sometimes 
  be 
  formed 
  in 
  what 
  Bischof 
  terms 
  the 
  " 
  wet 
  way," 
  a 
  

   fact 
  that 
  has 
  already 
  been 
  demonstrated 
  by 
  that 
  author 
  in 
  respect 
  

   of 
  felspar, 
  and 
  less 
  clearly 
  shown 
  in 
  the 
  case 
  of 
  hornblende 
  f 
  . 
  

  

  I 
  shall 
  have 
  to 
  allude 
  to 
  the 
  case 
  of 
  hornblende 
  and 
  felspar 
  further 
  

   on, 
  but 
  I 
  may 
  mention 
  here 
  that 
  the 
  agency 
  of 
  water 
  in 
  the 
  con- 
  

   version 
  of 
  augite 
  into 
  hornblende 
  may 
  be 
  distinctly 
  traced 
  in 
  the 
  

   slices 
  that 
  still 
  contain 
  pyroxene, 
  for 
  the 
  canals 
  left 
  by 
  the 
  percola- 
  

   tion 
  of 
  the 
  water 
  may 
  be 
  clearly 
  observed 
  in 
  the 
  hornblende 
  when 
  

   examined 
  with 
  a 
  i-inch 
  objective. 
  Countless 
  instances 
  of 
  this 
  may 
  

   be 
  seen. 
  

  

  These 
  slices 
  also 
  afford 
  evidence 
  that, 
  in 
  some 
  cases 
  at 
  all 
  events, 
  

   the 
  mica 
  found 
  in 
  them 
  has 
  been 
  formed 
  in 
  the 
  wet 
  way. 
  One 
  

   specimen 
  in 
  particular, 
  a 
  fragment 
  from 
  the 
  " 
  granulitic 
  " 
  group 
  at 
  

   Kennack 
  Cove, 
  deserves 
  especial 
  attention. 
  Macroscopically 
  considered, 
  

   this 
  looks 
  very 
  much 
  like 
  a 
  fragmental 
  rock 
  and 
  seems 
  to 
  consist 
  of 
  

  

  * 
  J. 
  D. 
  Dana's 
  ' 
  System 
  of 
  Mineralogy,' 
  5th 
  ed. 
  p. 
  283, 
  and 
  E. 
  S. 
  Dana's 
  

   ' 
  Text-Book,' 
  2nd 
  ed. 
  p. 
  285. 
  

  

  t 
  ' 
  Elements 
  of 
  Chemical 
  and 
  Physical 
  Geology,' 
  by 
  G-ustav 
  Bischof. 
  

  

  