﻿20 
  PEOF. 
  T. 
  G. 
  BONNET 
  ON 
  THE 
  SECTIONS 
  NEAE 
  [Feb. 
  1 
  897, 
  

  

  and 
  a 
  second 
  thinner 
  and 
  apparently 
  more 
  limited 
  band 
  of 
  the 
  

   latter 
  rock 
  occurs 
  above 
  it. 
  In 
  the 
  section 
  at 
  Bealp 
  L 
  a 
  rather 
  

   similar 
  limestone 
  overlies 
  the 
  slabby 
  marble, 
  but 
  the 
  second 
  mass 
  

   of 
  that 
  rock 
  is 
  not 
  seen. 
  It 
  may 
  occur, 
  however, 
  for 
  there 
  is 
  a 
  

   considerable 
  interval 
  of 
  covered 
  ground 
  just 
  where 
  it 
  ought 
  to 
  

   crop 
  out. 
  

  

  The 
  possibility 
  that 
  this 
  subcrystalline 
  Jurassic 
  rock 
  might 
  contain 
  

   small 
  fragments 
  of 
  the 
  marble 
  has 
  more 
  than 
  once 
  occurred 
  to 
  me, 
  but 
  

   on 
  this 
  point 
  I 
  have 
  failed 
  to 
  obtain 
  conclusive 
  evidence. 
  Here 
  

   and 
  there 
  one 
  detects 
  with 
  the 
  microscope 
  single 
  grains 
  of 
  calcite, 
  

   or 
  associated 
  groups 
  of 
  a 
  few 
  grains 
  of 
  calcite 
  and 
  quartz, 
  which 
  

   present 
  an 
  approach 
  to 
  a 
  definite 
  boundary 
  and 
  resemble 
  small 
  

   fragments 
  of 
  the 
  marble 
  ; 
  but, 
  as 
  the 
  principal 
  constituents 
  of 
  the 
  

   two 
  rocks 
  are 
  the 
  same, 
  anything 
  like 
  a 
  boundary-line 
  is 
  not 
  easily 
  

   distinguished, 
  and 
  it 
  may 
  be 
  that 
  the 
  agent, 
  to 
  which 
  such 
  meta- 
  

   morphism 
  as 
  the 
  rock 
  has 
  undergone 
  is 
  due, 
  has 
  operated 
  a 
  little 
  

   sporadically. 
  Still 
  I 
  think 
  that 
  this 
  possibility 
  should 
  be 
  kept 
  

   in 
  view 
  by 
  anyone 
  studying 
  the 
  rock. 
  But 
  the 
  composition 
  and 
  

   condition 
  of 
  the 
  band 
  in 
  immediate 
  contact 
  with 
  the 
  marble, 
  and 
  the 
  

   state 
  of 
  the 
  upper 
  part 
  of 
  the 
  latter, 
  strongly 
  suggest 
  the 
  existence 
  

   of 
  a 
  thrust-fault. 
  That 
  might 
  follow, 
  however, 
  the 
  direction 
  of 
  

   the 
  junction-surface 
  between 
  two 
  rocks 
  of 
  different 
  strength. 
  But 
  

   whether 
  the 
  present 
  succession 
  of 
  the 
  rocks 
  be 
  the 
  original 
  one 
  or 
  be 
  

   only 
  due 
  to 
  faulting, 
  the 
  result 
  of 
  this 
  examination 
  and 
  of 
  further 
  

   study 
  of 
  the 
  rocks 
  in 
  the 
  great 
  trough 
  of 
  the 
  Upper 
  Eh 
  one 
  valley 
  

   convinces 
  me 
  that 
  it 
  is 
  more 
  probable 
  that 
  the 
  marble 
  is 
  not 
  a 
  

   member 
  of 
  the 
  Jurassic 
  system, 
  but 
  a 
  much 
  more 
  ancient 
  rock, 
  

   than 
  that 
  metamorphism 
  has 
  acted 
  in 
  a 
  way 
  unaccountably 
  sporadic 
  

   and 
  capricious. 
  

  

  Posts 
  ceipt. 
  

  

  This 
  paper 
  was 
  completed 
  shortly 
  before 
  I 
  left 
  England 
  early 
  in 
  

   July 
  1896. 
  Most 
  of 
  my 
  holiday 
  was 
  devoted 
  to 
  examining, 
  in 
  

   company 
  with 
  my 
  friend 
  Mr. 
  J. 
  Eccles, 
  E.G.S., 
  sections 
  between 
  

   Ilanz 
  and 
  Spliigen 
  and 
  the 
  district 
  south 
  of 
  the 
  Eheinwald-Thal. 
  

   Hereabouts 
  ' 
  slabby 
  ' 
  marble 
  is 
  an 
  unusually 
  abundant 
  constituent 
  

   of 
  the 
  group 
  of 
  calc-mica 
  schists 
  (including 
  quartz 
  -schists 
  and 
  

   * 
  green 
  schists 
  '). 
  The 
  distinctive 
  characters 
  of 
  the 
  marble, 
  and 
  the 
  

   marked 
  differences 
  between 
  this 
  group 
  of 
  crystalline 
  schists 
  and 
  

   the 
  slaty 
  or 
  calcareous 
  rocks 
  of 
  Mesozoic 
  age 
  in 
  the 
  Alps, 
  were 
  

   impressed, 
  if 
  possible, 
  more 
  strongly 
  than 
  ever, 
  upon 
  my 
  mind. 
  

  

  Discussion. 
  

  

  The 
  Eev. 
  Edwin 
  Hill 
  said 
  that 
  he 
  could 
  speak 
  only 
  of 
  the 
  

   Eurka 
  section. 
  The 
  two 
  rocks 
  seemed 
  always 
  in 
  conformity, 
  but 
  

   always 
  with 
  signs 
  of 
  crush 
  between, 
  and 
  always 
  showed 
  marked 
  

   differences 
  in 
  strength, 
  pointing 
  to 
  difference 
  in 
  age. 
  

  

  1 
  Op, 
  cit. 
  p. 
  293, 
  3' 
  in 
  the 
  section. 
  

  

  