﻿82 
  PROF. 
  T. 
  G. 
  BONNET 
  ON 
  TWO 
  TEAVEESES 
  OE 
  TEE 
  

  

  base 
  of 
  the 
  hill, 
  crowned 
  by 
  the 
  celebrated 
  forts, 
  is 
  a 
  felspar-acti- 
  

   nolite 
  rock 
  *, 
  possibly 
  of 
  igneous 
  origin, 
  followed 
  by 
  mica-schist, 
  

   and 
  a 
  dull 
  green 
  rock 
  banded 
  with 
  epidote, 
  dipping 
  much 
  as 
  before. 
  

   The 
  rock 
  in 
  this 
  neighbourhood 
  is 
  stronger 
  and 
  less 
  easily 
  weathered 
  

   than 
  that 
  higher 
  up 
  the 
  valley, 
  and 
  recalled 
  to 
  my 
  mind 
  some 
  of 
  

  

  Fig. 
  4, 
  — 
  Diagram 
  of 
  '" 
  stratification-foliation" 
  in 
  Calc-mica-schist 
  

   near 
  Col 
  cle 
  Sestrie 
  r 
  res. 
  

  

  The 
  lines 
  roughly 
  indicate 
  micaceous 
  layers 
  ; 
  the 
  long 
  arrow 
  is 
  parallel 
  with 
  

   the 
  " 
  cleavage-foliation 
  " 
  of 
  the 
  mass 
  ; 
  the 
  small 
  arrow 
  shows 
  the 
  place 
  

   where 
  a 
  specimen 
  was 
  taken 
  for 
  examination 
  (p. 
  103). 
  

  

  the 
  chloritic 
  and 
  micaceous 
  rocks 
  about 
  Zermatt 
  or 
  near 
  St. 
  Vincent 
  

   in 
  the 
  Yal 
  d'Aoste 
  f. 
  Below 
  Fenestrelle 
  this 
  change 
  in 
  character 
  

   becomes 
  yet 
  more 
  marked. 
  The 
  rocks 
  now 
  are 
  more 
  massive, 
  form- 
  

   ing 
  bolder 
  crags 
  which 
  are 
  no 
  longer 
  masked 
  by 
  a 
  talus 
  of 
  shivery 
  

   schist 
  ; 
  in 
  short, 
  the 
  same 
  change 
  in 
  the 
  scenery 
  may 
  be 
  observed 
  

  

  * 
  Consists 
  chiefly 
  of 
  epidote, 
  actinolitic 
  hornblende, 
  quartz, 
  felspar 
  and 
  hsema- 
  

   tite, 
  with 
  some 
  sphene 
  and 
  rutile. 
  The 
  microscopic 
  structure 
  is 
  interesting 
  in 
  

   many 
  ways, 
  but 
  it 
  is 
  enough 
  for 
  my 
  present 
  purpose 
  to 
  say 
  that 
  subsequent 
  

   mineral 
  rearrangement 
  has 
  made 
  it 
  difficult 
  to 
  be 
  sure 
  of 
  the 
  original 
  condition 
  

   of 
  the 
  rock, 
  but 
  I 
  think 
  that 
  it 
  probably 
  was 
  igneous, 
  and 
  that 
  pressure 
  has 
  not 
  

   been 
  the 
  sole 
  agent 
  of 
  change. 
  

  

  t 
  Minerals 
  : 
  quartz, 
  epidote, 
  mica, 
  white 
  and 
  brown, 
  chlorite 
  (probably 
  in 
  

   part, 
  at 
  least, 
  replacing 
  the 
  latter), 
  garnet 
  (red), 
  a 
  little 
  rutile 
  and 
  a 
  colourless 
  

   doubly 
  refracting 
  mineral 
  of 
  ill-defined 
  limit 
  and 
  form, 
  probably 
  allied 
  to 
  zoisite 
  

   or 
  epidote. 
  The 
  rock 
  is 
  distinctly 
  foliated 
  and 
  banded. 
  The 
  constituents, 
  

   especially 
  the 
  white 
  mica, 
  are 
  fair-sized 
  and 
  well 
  defined, 
  as 
  if 
  freely 
  formed 
  ; 
  so 
  

   if 
  the 
  foliation 
  results 
  from 
  pressure, 
  a 
  good 
  deal 
  of 
  mineral 
  change 
  has 
  

   subsequently 
  occurred. 
  The 
  structure 
  is, 
  for 
  a 
  schist, 
  a 
  little 
  abnormal 
  ; 
  possibly 
  

   that 
  may 
  be 
  connected 
  with 
  the 
  presence 
  of 
  a 
  neighbouring 
  intrusive 
  mass. 
  

  

  