﻿108 
  PROP. 
  T. 
  Gt. 
  HOTKEY 
  01* 
  TWO 
  TBAVEESES 
  OF 
  THE 
  

  

  lerthal 
  at 
  once 
  struck 
  me 
  as 
  rather 
  abnormal. 
  They 
  were 
  more 
  

   compact, 
  less 
  saccharoidal, 
  than 
  I 
  had 
  been 
  accustomed 
  to 
  see, 
  w 
  hen 
  

   the3 
  T 
  were 
  among 
  crystalline 
  mica-schists. 
  The 
  microscope 
  shows 
  

   that 
  this 
  is 
  due 
  to 
  the 
  rock 
  having 
  been 
  more 
  or 
  less 
  pulverized 
  and 
  

   subsequently 
  recemented, 
  so 
  that 
  its 
  texture 
  bears 
  some 
  resemblance 
  

   to 
  that 
  of 
  the 
  Mesozoic 
  Alpine 
  Limestones. 
  Perhaps 
  I 
  should 
  add 
  

   that 
  I 
  am 
  well 
  acquainted 
  with 
  the 
  Tyrol 
  dolomites, 
  and 
  that 
  they 
  

   differ 
  in 
  some 
  respects 
  from 
  all 
  the 
  rocks 
  described 
  in 
  this 
  para- 
  

   graph, 
  macroscopically 
  and 
  microscopically. 
  Further, 
  it 
  is 
  only 
  at 
  

   Bruneckeri 
  that 
  any 
  doubt 
  could 
  arise 
  as 
  to 
  the 
  geological 
  horizon 
  

   of 
  the 
  limestone 
  ; 
  but 
  here, 
  I 
  think, 
  its 
  relations 
  to 
  the 
  schists 
  and 
  

   its 
  position 
  with 
  regard 
  to 
  the 
  neighbouring 
  dolomites 
  becomes 
  clear 
  

   on 
  examination. 
  

  

  (e) 
  Four 
  specimens, 
  a, 
  (3,y, 
  from 
  the 
  gorge 
  above 
  Windisch-Matrei 
  

   (p. 
  87), 
  B 
  from 
  the 
  ravine 
  near 
  Mittersill 
  (p. 
  90). 
  All 
  contain 
  

   chlorite, 
  often 
  in 
  flakes 
  about 
  # 
  02 
  inch 
  long. 
  Possibly 
  more 
  than 
  

   one 
  species 
  is 
  present, 
  but 
  most 
  of 
  it 
  is 
  of 
  a 
  yellowish 
  green 
  with 
  

   transmitted 
  light, 
  a 
  fairly 
  bright 
  sap-green 
  with 
  vibrations 
  perpen- 
  

   dicular 
  to 
  the 
  vertical 
  axis, 
  and 
  a 
  kind 
  of 
  straw-yellow 
  with 
  those 
  

   parallel 
  with 
  it, 
  and 
  the 
  extinction 
  appears 
  to 
  indicate 
  a 
  mineral 
  of 
  

   the 
  hexagonal 
  system. 
  Yellowish 
  epidote 
  is 
  also 
  present 
  in 
  variable 
  

   quantities. 
  In 
  (a), 
  from 
  the 
  top 
  of 
  the 
  mass, 
  the 
  epidote 
  in 
  parts 
  

   of 
  the 
  slide 
  occurs 
  in 
  minute 
  granules, 
  with 
  a 
  " 
  dusty 
  " 
  look, 
  render- 
  

   ing 
  the 
  structure 
  obscure, 
  but 
  in 
  other 
  parts 
  in 
  well-defined 
  grains 
  

   and 
  prisms, 
  often 
  about 
  "01 
  inch 
  long. 
  There 
  are 
  some 
  character- 
  

   istic 
  crystalline 
  grains 
  of 
  kyanite, 
  containing 
  the 
  dark 
  enclosures 
  

   with 
  linear 
  arrangements 
  described 
  above 
  (p. 
  100), 
  and 
  occasionally 
  

   small 
  grains 
  of 
  epidote. 
  A 
  little 
  quartz 
  and 
  some 
  grains 
  of 
  iron- 
  

   oxide 
  occur, 
  with 
  much 
  opacite 
  lying 
  along 
  the 
  lines 
  of 
  cleavage- 
  

   foliation. 
  In 
  (/3), 
  from 
  some 
  distance 
  down 
  in 
  the 
  mass, 
  almost 
  half 
  

   the 
  slide 
  consists 
  of 
  somewhat 
  rounded 
  grains 
  about 
  *02 
  inch 
  in 
  

   diameter, 
  of 
  a 
  clear 
  mineral 
  containing 
  numerous 
  minute 
  flakes 
  of 
  

   chlorite 
  and 
  granules 
  of 
  epidote. 
  These 
  constituents 
  exhibit 
  a 
  rough 
  

   parallelism 
  throughout 
  the 
  slide. 
  It 
  is 
  rather 
  difficult 
  to 
  decide 
  

   upon 
  the 
  nature 
  of 
  this 
  clear 
  mineral, 
  but 
  some 
  grains 
  are 
  twinned, 
  

   and 
  it 
  appears 
  to 
  one 
  to 
  correspond 
  better 
  with 
  kyanite 
  than 
  with 
  a 
  

   felspar. 
  There 
  are 
  a 
  few 
  grains 
  of 
  an 
  iron-oxide, 
  probably 
  haematite, 
  

   and 
  in 
  one 
  part 
  is 
  a 
  little 
  dolomite 
  or 
  possibly 
  chalybite. 
  (y) 
  epi- 
  

   dotic 
  schist 
  underlying 
  the 
  interband 
  of 
  calc-schist. 
  In 
  parts 
  of 
  

   this, 
  epidote 
  is 
  abundant 
  and 
  well 
  developed. 
  The 
  supposed 
  kyanite 
  

   occurs, 
  but 
  there 
  is 
  certainly 
  some 
  quartz, 
  and 
  crystalline 
  grains 
  of 
  

   haematite 
  (?) 
  are 
  more 
  common. 
  (£), 
  from 
  near 
  Mittersill, 
  seems 
  to 
  

   have 
  rather 
  more 
  quartz, 
  calcite, 
  and 
  iron-oxide 
  than 
  the 
  others, 
  

   with 
  less 
  epidote 
  ; 
  but 
  the 
  differences 
  appear 
  to 
  me 
  only 
  varietal. 
  

   These 
  rocks 
  all 
  give 
  evidence 
  of 
  mechanical 
  disturbance 
  subsequent 
  

   to 
  the 
  first 
  crystallization. 
  

  

  I 
  am 
  indebted 
  to 
  Mr. 
  E. 
  Greenly 
  for 
  the 
  following 
  analyses 
  of 
  

   varieties 
  of 
  these 
  chloritic 
  schists, 
  made 
  in 
  the 
  chemical 
  laboratory 
  

   at 
  University 
  College 
  : 
  — 
  

  

  