﻿92 
  PROF. 
  T. 
  G. 
  BOls^EY 
  ON 
  TWO 
  TRAVERSES 
  OE 
  THE 
  

  

  almost 
  uncleared, 
  while 
  the 
  micaceous, 
  lead-coloured 
  schist 
  is 
  almost 
  

   as 
  fissile 
  as 
  a 
  slate. 
  

  

  Beyond 
  this 
  glen, 
  the 
  road 
  turns 
  away 
  from 
  the 
  Salza 
  valley, 
  and 
  

   mounts 
  in 
  a 
  northerly 
  direction 
  to 
  the 
  Pass 
  Thurn 
  (-±180 
  feet). 
  Two 
  

   types 
  of 
  rocks 
  are 
  exposed 
  at 
  intervals, 
  one 
  a 
  " 
  Thonglimmerschiefer" 
  

   the 
  other, 
  and 
  rarer, 
  a 
  more 
  massive 
  rock, 
  schistose 
  in 
  aspect, 
  

   apparently 
  a 
  kersantite 
  modified 
  by 
  pressure. 
  The 
  former 
  rock 
  is 
  

   at 
  times 
  so 
  completely 
  crushed 
  that 
  in 
  the 
  field 
  it 
  is 
  difficult 
  to 
  de- 
  

   cide 
  whether 
  it 
  is 
  phyllite 
  or 
  crushed 
  schist. 
  Sometimes 
  it 
  might 
  

   well 
  have 
  been 
  referred 
  to 
  the 
  former, 
  but 
  now 
  and 
  then 
  harder 
  

   bands 
  had 
  the 
  characteristics 
  of 
  true 
  schists. 
  The 
  fissile 
  papery 
  

   varieties 
  are 
  unfitted 
  for 
  microscopic 
  examination, 
  but 
  one 
  of 
  the 
  

   latter 
  (Appendix, 
  p. 
  106) 
  is 
  a 
  true 
  schist. 
  Hence 
  I 
  conclude 
  that 
  

   Yon 
  Hauer 
  is 
  probably 
  quite 
  right 
  in 
  mapping 
  all 
  on 
  the 
  south 
  side 
  

   of 
  the 
  pass 
  as 
  " 
  Thonglimmerschiefer" 
  but 
  that 
  the 
  rock 
  has 
  been 
  in 
  

   places 
  almost 
  pulverized. 
  The 
  well-known 
  sections 
  south 
  of 
  Torcross 
  

   in 
  Devon 
  were 
  constantly 
  recalled 
  to 
  my 
  mind, 
  but 
  in 
  this 
  locality 
  the 
  

   evidence 
  at 
  first 
  sight 
  seemed 
  even 
  more 
  favourable 
  to 
  the 
  idea 
  of 
  a 
  

   transition 
  from 
  true 
  schist 
  to 
  a 
  satiny 
  slate. 
  I 
  much 
  regretted 
  that 
  

   circumstances 
  prevented 
  me 
  from 
  making 
  a 
  prolonged 
  halt 
  at 
  the 
  

   top 
  of 
  the 
  pass, 
  and 
  following 
  up 
  the 
  rocks 
  for 
  some 
  distance 
  east 
  

   and 
  west. 
  Still 
  I 
  feel 
  convinced 
  that 
  the 
  mapping 
  is 
  correct, 
  and 
  

   that 
  here, 
  as 
  is 
  commonly 
  the 
  case, 
  the 
  most 
  marked 
  effects 
  of 
  

   pressure 
  have 
  been 
  produced 
  in 
  the 
  upper 
  part 
  of 
  the 
  more 
  crystal- 
  

   line 
  rock. 
  Schist, 
  with 
  a 
  cleavage-foliation 
  dipping, 
  where 
  mea- 
  

   sured, 
  between 
  X. 
  and 
  N.N.E., 
  occurs 
  on 
  the 
  first 
  part 
  of 
  the 
  descent, 
  

   but 
  lower 
  down 
  it 
  becomes 
  more 
  like 
  a 
  normal 
  schist 
  and 
  rather 
  

   greener 
  in 
  colour. 
  After 
  this 
  the 
  valley 
  opens 
  out, 
  and 
  the 
  road 
  

   descends 
  to 
  Kitzbiihel 
  through 
  rich 
  pastoral 
  scenery, 
  beneath 
  which 
  

   the 
  Greywacke 
  (Silurian) 
  of 
  Yon 
  Hauer 
  is 
  concealed. 
  Sections, 
  

   however, 
  of 
  the 
  latter 
  can 
  be 
  examined 
  in 
  and 
  near 
  Kitzbiihel. 
  I 
  

   have 
  studied 
  microscopically 
  a 
  specimen 
  obtained 
  near 
  a 
  mine 
  

   (gold 
  ?) 
  south 
  of 
  the 
  town. 
  The 
  rock, 
  though 
  it 
  has 
  undergone 
  con- 
  

   siderable 
  pressure, 
  and 
  might 
  be 
  called 
  a 
  phyllite, 
  is 
  quite 
  different 
  

   from 
  any 
  member 
  of 
  the 
  "Thonglimmerschiefer" 
  group. 
  In 
  short, 
  this 
  

   group 
  does 
  not 
  appear 
  more 
  metamorphosed 
  than 
  one 
  of 
  the 
  older 
  

   Palaeozoic 
  series 
  of 
  Britain 
  in 
  a 
  region 
  where 
  the 
  rocks 
  have 
  been 
  

   much 
  compressed. 
  It 
  is 
  succeeded 
  unconformably 
  by 
  cream-coloured 
  

   Mesozoic 
  limestones. 
  

  

  (e) 
  Hie 
  Zillerthal 
  and 
  the 
  Brenner. 
  

  

  These 
  sections 
  cut 
  deep 
  into 
  the 
  northern 
  side 
  of 
  the 
  central 
  

   chain, 
  and 
  enabled 
  us 
  to 
  add 
  to 
  the 
  evidence 
  obtained 
  in 
  our 
  traverse. 
  

   According 
  to 
  Yon 
  Hauer, 
  a 
  narrow 
  band 
  of 
  Greywacke, 
  a 
  prolonga- 
  

   tion 
  of 
  that 
  mentioned 
  above, 
  intervenes 
  between 
  the 
  base 
  of 
  the 
  

   Jurassic 
  series 
  and 
  the 
  "Thonglimmerschiefer" 
  This 
  we 
  were 
  unfor- 
  

   tunately 
  prevented 
  from 
  examining 
  in 
  situ, 
  though 
  we 
  saw 
  it 
  in 
  frag- 
  

   ments. 
  "Thonglimmerschiefer" 
  of 
  a 
  perfectly 
  normal 
  character 
  is 
  seen 
  

   abundantly, 
  first 
  in 
  fragments 
  brought 
  down 
  by 
  lateral 
  torrents, 
  

  

  