﻿CRYSTALLINE 
  ROCKS 
  OP 
  THE 
  ALPS. 
  83 
  

  

  when, 
  in 
  other 
  parts 
  of 
  the 
  Alps, 
  we 
  are 
  quitting 
  the 
  " 
  Upper 
  Schists 
  " 
  

   and 
  entering 
  the 
  stronger 
  more 
  coarsely 
  crystalline 
  series 
  which 
  

   often 
  underlies 
  them. 
  Unfortunately 
  we 
  had 
  no 
  opportunity 
  of 
  

   examining 
  the 
  rock 
  (which 
  we 
  deemed 
  to 
  be 
  a 
  mica-schist) 
  in 
  situ 
  

   till 
  we 
  reached 
  La 
  Balme, 
  where 
  we 
  found 
  a 
  schist 
  with 
  bands 
  of 
  

   mica 
  (in 
  rather 
  large 
  flakes) 
  and 
  a 
  fine-grained 
  gneissoid 
  rock, 
  the 
  

   association 
  of 
  the 
  two 
  being 
  suggestive 
  of 
  some 
  kind 
  of 
  stratification 
  

   of 
  the 
  original 
  constituents. 
  The 
  rock 
  resembled 
  one 
  in 
  the 
  Lepon- 
  

   tine 
  series 
  near 
  Altanca 
  *. 
  The 
  dip 
  was 
  about 
  30° 
  to 
  IN". 
  10° 
  W. 
  

   Yet 
  lower 
  down 
  comes 
  a 
  strong 
  brownish 
  mica-sehist, 
  with 
  little, 
  if 
  

   any, 
  mineral 
  banding 
  and 
  no 
  strongly 
  marked 
  foliation, 
  which 
  has 
  

   nearly 
  the 
  same 
  strike, 
  but 
  is 
  almost 
  vertical, 
  dipping 
  perhaps 
  slightly 
  

   on 
  the 
  northern 
  side 
  f 
  . 
  This 
  rock 
  continues 
  with 
  little 
  variation 
  

   for 
  a 
  considerable 
  distance 
  ; 
  but 
  about 
  a 
  mile 
  before 
  reaching 
  La 
  

   Perouse, 
  a 
  quarry 
  has 
  been 
  opened 
  in 
  a 
  paler-coloured 
  gneiss. 
  The 
  

   brownish 
  mica-schist, 
  however, 
  occurs 
  again 
  below 
  the 
  town. 
  After 
  

   an 
  interval 
  without 
  any 
  outcrops 
  near 
  the 
  road, 
  we 
  find 
  just 
  below 
  

   San 
  Germano 
  a 
  gneissoid 
  rock, 
  not 
  impossibly 
  of 
  igneous 
  origin, 
  

   dipping 
  (if 
  the 
  faint 
  indications 
  of 
  structure 
  can 
  be 
  trusted) 
  approxi- 
  

   mately 
  at 
  45° 
  to 
  S.E. 
  It 
  becomes 
  slightly 
  more 
  gneissoid 
  and 
  is 
  

   succeeded 
  in 
  about 
  a 
  furlong 
  by 
  a 
  finer-grained 
  rock 
  of 
  brownish 
  

   colour 
  inclining 
  sometimes 
  to 
  greenish 
  grey. 
  This 
  exhibits 
  a 
  mode- 
  

   rately 
  definite 
  foliation, 
  but 
  includes 
  masses 
  of 
  a 
  darker 
  colour 
  ; 
  these 
  

   may 
  be 
  nodes, 
  but 
  certainly 
  in 
  some 
  cases 
  they 
  look 
  like 
  fragments 
  

   of 
  a 
  crystalline 
  rock. 
  The 
  dip 
  of 
  the 
  foliation 
  (there 
  is 
  no 
  mineral 
  

   banding) 
  is 
  roughly 
  to 
  S. 
  at 
  about 
  50°. 
  Another 
  quarry 
  still 
  lower 
  

   down 
  gives 
  a 
  rather 
  more 
  definite 
  dip 
  (45° 
  to 
  E.S.E.). 
  Below 
  this 
  

   the 
  valley 
  opens 
  out 
  as 
  we 
  approach 
  Pinerolo 
  and 
  reach 
  the 
  margin 
  

   of 
  the 
  plain 
  of 
  Piedmont. 
  

  

  II. 
  The 
  Eastern" 
  Alps 
  prom 
  Lienz 
  to 
  Kitzbuhel. 
  

   (a) 
  Nomenclature 
  of 
  Bocks. 
  

  

  According 
  to 
  Von 
  Hauer's 
  map 
  of 
  the 
  Eastern 
  Alps, 
  which, 
  though 
  

   on 
  a 
  small 
  scale, 
  we 
  found 
  an 
  excellent 
  piece 
  of 
  petrographical 
  work, 
  

   the 
  fundamental 
  rock 
  is 
  a 
  group 
  of 
  gneisses, 
  called 
  the 
  Central 
  

   Gneiss 
  ; 
  to 
  this 
  succeeds 
  ordinary 
  gneiss, 
  and 
  to 
  this 
  mica-schist. 
  

   Last 
  of 
  all 
  comes 
  a 
  formation 
  called 
  by 
  him 
  " 
  Thonschiefer" 
  Horn- 
  

   blendic 
  and 
  chloritic 
  schists 
  and 
  crystalline 
  limestone 
  occur 
  rather 
  

   locally 
  at 
  horizons 
  the 
  position 
  of 
  which 
  will 
  be 
  described 
  further 
  

   on. 
  North 
  of 
  the 
  central 
  range 
  is 
  a 
  band 
  of 
  greywacke 
  and 
  slate, 
  

   which 
  is 
  referred 
  to 
  the 
  Silurian, 
  and 
  can 
  be 
  traced 
  for 
  many 
  miles. 
  

   The 
  northern 
  and 
  the 
  southern 
  range 
  consist 
  mainly 
  of 
  sedimentary 
  

   rocks, 
  chiefly 
  limestones 
  or 
  dolomite, 
  which, 
  as 
  is 
  well 
  known, 
  are 
  of 
  

   Triassic 
  or 
  later 
  age. 
  These 
  also 
  in 
  all 
  probability 
  once 
  extended 
  

  

  * 
  Quart, 
  Journ. 
  Geol. 
  Soc. 
  1886, 
  Presid. 
  Address, 
  p. 
  69. 
  

   t 
  For 
  the 
  microscopic 
  structure 
  of 
  these 
  and 
  the 
  following 
  rocks, 
  see 
  Appendix., 
  

   p. 
  103. 
  

  

  g2 
  

  

  