﻿104 
  PEOE. 
  T. 
  G. 
  P.OXXEY 
  OX 
  TWO 
  TEAYEESES 
  OE 
  THE 
  

  

  recent 
  crushing. 
  The 
  grains 
  of 
  quartz 
  and 
  felspar 
  have 
  a 
  slightly 
  

   wavy 
  outline, 
  and 
  form 
  a 
  sort 
  of 
  mosaic 
  or 
  agglutination, 
  and 
  the 
  

   two 
  minerals 
  are 
  frequently 
  difficult 
  to 
  distinguish. 
  Mierolithic 
  

   enclosures 
  are 
  rather 
  common, 
  such 
  as 
  epidote, 
  zoisite, 
  and 
  perhaps 
  

   garnet. 
  The 
  constituents 
  of 
  the 
  rocks 
  exhibit 
  a 
  certain 
  parallelism, 
  

   but 
  little 
  approach 
  to 
  a 
  true 
  mineral 
  banding. 
  In 
  (a) 
  small 
  garnets 
  

   (reddish) 
  are 
  rather 
  common, 
  generally 
  rounded 
  in 
  outline. 
  The 
  

   biotite 
  more 
  frequently 
  passes 
  into 
  a 
  pale 
  greenish 
  mineral, 
  and 
  a 
  

   little 
  pale 
  hornblende 
  may 
  be 
  present. 
  Small 
  grains 
  and 
  crystals 
  of 
  

   a 
  mineral 
  resembling 
  epidote 
  are 
  numerous 
  ; 
  some 
  give 
  the 
  usual 
  

   bright 
  tints 
  of 
  that 
  mineral, 
  but 
  many 
  only 
  afford 
  low 
  blues 
  of 
  the 
  

   second 
  order, 
  with, 
  as 
  a 
  rule, 
  oblique 
  extinction. 
  Probably 
  more 
  

   than 
  one 
  variety 
  of 
  the 
  mineral 
  is 
  present, 
  and 
  perhaps 
  a 
  little 
  zoisite. 
  

   In 
  (5) 
  there 
  is 
  more 
  approach 
  to 
  a 
  mineral 
  banding; 
  the 
  mica 
  is 
  

   in 
  better 
  preservation 
  ; 
  garnets 
  are 
  rare 
  or 
  absent. 
  The 
  normal 
  

   epidote 
  is 
  rather 
  abundant, 
  with, 
  however, 
  the 
  low-coloured 
  variety, 
  

   and 
  some 
  well-defined 
  zoisite 
  : 
  (c) 
  has 
  a 
  considerable 
  amount 
  of 
  

   zoisite 
  * 
  with 
  a 
  little 
  garnet 
  and 
  sphene. 
  The 
  peculiar 
  structure 
  of 
  

   these 
  rocks 
  separates 
  them 
  from 
  the 
  ordinary 
  gneisses 
  and 
  schists. 
  

   It 
  suggests 
  the 
  possibility 
  of 
  an 
  igneous 
  origin, 
  wbich, 
  in 
  one 
  case 
  at 
  

   least 
  (c), 
  is 
  corroborated 
  by 
  the 
  field-evidence. 
  Pressure 
  may 
  have 
  

   been 
  an 
  agent 
  in 
  the 
  metamorphism, 
  but 
  it 
  must 
  have 
  been 
  followed 
  

   by 
  almost 
  complete 
  mineral 
  rearrangement. 
  The 
  structure 
  differs 
  

   entirely 
  from 
  those 
  exhibited 
  in 
  the 
  granites, 
  gneisses, 
  and 
  schists 
  of 
  

   other 
  parts 
  of 
  the 
  Alps, 
  which 
  we 
  may 
  reasonably 
  consider 
  the 
  

   results 
  of 
  the 
  great 
  disturbances 
  of 
  Tertiary 
  date. 
  Moreover 
  the 
  

   foliation 
  produced 
  by 
  these 
  is, 
  commonly, 
  roughly 
  parallel 
  in 
  its 
  

   strike 
  with 
  the 
  dominant 
  trends 
  of 
  the 
  ranges. 
  Here, 
  however, 
  it 
  

   runs 
  almost 
  at 
  right 
  angles 
  to 
  the 
  direction 
  which 
  we 
  should 
  have 
  

   expected, 
  and 
  which 
  we 
  actually 
  found 
  in 
  the 
  neighbourhood 
  of 
  the 
  

   watershed. 
  The 
  natural 
  inference, 
  then, 
  would 
  be, 
  that 
  we 
  are 
  deal- 
  

   ing 
  here 
  with 
  a 
  foliation 
  of 
  earlier 
  date 
  than 
  the 
  Tertiary 
  disturb- 
  

   ances. 
  

  

  B. 
  Easteex 
  Alps. 
  

  

  (a) 
  Central 
  gneiss 
  (Yon 
  Hauer), 
  Velber-Tauern 
  district 
  

   (pp. 
  89, 
  90). 
  

  

  Of 
  the 
  more 
  hornblendic 
  varieties, 
  three 
  specimens 
  have 
  been 
  ex- 
  

   amined. 
  In 
  all, 
  hornblende 
  (normal), 
  quartz, 
  and 
  more 
  or 
  less 
  felspar 
  

   are 
  present, 
  sphene 
  is 
  generally 
  found, 
  and 
  more 
  or 
  less 
  ferrite 
  or 
  

   opacite. 
  The 
  specimen 
  " 
  from 
  the 
  valley 
  bed 
  above 
  the 
  Tauern 
  

   Haus 
  " 
  contains 
  a 
  little 
  of 
  a 
  mineral 
  resembling 
  kyanite 
  : 
  it 
  may 
  be 
  

   a 
  modified 
  dolerite 
  or 
  diorite, 
  but 
  the 
  structural 
  change 
  cannot 
  be 
  

   recent, 
  complete 
  mineral 
  rearrangement 
  having 
  taken 
  place. 
  

   Another 
  specimen, 
  taken 
  about 
  800 
  feet 
  above 
  Gschloss, 
  on 
  the 
  way 
  to 
  

  

  * 
  I 
  have 
  to 
  thank 
  Mr. 
  Teall 
  for 
  enabling 
  me 
  to 
  identify 
  this 
  mineral. 
  As 
  it 
  

   happened, 
  though 
  I 
  had 
  an 
  abundance 
  of 
  the 
  so-called 
  saussurite, 
  I 
  had 
  no 
  good 
  

   typical 
  zoisite 
  in 
  my 
  collection. 
  

  

  