﻿ON 
  TRAVERSES 
  OF 
  THE 
  CRFSTALLtNE 
  ROCKS 
  OF 
  THE 
  ALPS. 
  67 
  

  

  4. 
  Notes 
  on 
  two 
  Traverses 
  of 
  the 
  Crystalline 
  Rocks 
  of 
  the 
  Alps. 
  

   By 
  T. 
  G. 
  Bonnet, 
  D.Sc, 
  LL.D., 
  F.K.S., 
  F.G.S., 
  Professor 
  of 
  

   Geology 
  in 
  University 
  College, 
  London, 
  and 
  Fellow 
  of 
  St. 
  

   John's 
  College, 
  Cambridge. 
  (Read 
  December 
  5, 
  1888.) 
  

  

  I. 
  The 
  Western 
  Alps 
  from 
  Grenoble 
  to 
  Turin. 
  

  

  A. 
  Grenoble 
  to 
  Briancon. 
  

  

  (a) 
  From 
  Vizille 
  to 
  Bourg 
  d'Oisans 
  : 
  Belledonne 
  range. 
  

   (]3) 
  Bourg 
  d'Oisans 
  to 
  Le 
  Dauphin 
  : 
  Grandes-Eousses 
  range, 
  

   (y) 
  Le 
  Dauphin 
  to 
  Briancon 
  by 
  the 
  Col 
  du 
  Lautaret. 
  

  

  B. 
  Briancon 
  to 
  Turin. 
  

  

  (a) 
  Section 
  of 
  tbe 
  Mont 
  Genevre 
  Pass. 
  

   (/3) 
  Section 
  of 
  the 
  Col 
  de 
  Sestrieres. 
  

  

  II. 
  The 
  Eastern 
  Alps 
  from 
  Lienz 
  to 
  Kitzbuhel. 
  

  

  (a) 
  Nomenclature 
  of 
  rocks. 
  

  

  (/3) 
  The 
  Pusterthal 
  and 
  neighbourhood. 
  

  

  (y) 
  Lienz 
  to 
  Mittersill. 
  

  

  (S) 
  Mittersill 
  to 
  Kitzbiihel. 
  

  

  (e) 
  The 
  Zillerthal 
  and 
  the 
  Brenner. 
  

  

  III. 
  Conclusions. 
  

  

  IV. 
  Appendix 
  : 
  Description 
  of 
  Microscopic 
  Structures. 
  

  

  A. 
  Western 
  Alps. 
  

  

  (a) 
  Schists 
  of 
  tbe 
  Combe 
  de 
  Gayet. 
  

  

  (|6) 
  Gneiss 
  of 
  the 
  Combe 
  de 
  Malaval. 
  

  

  (y) 
  Carboniferous 
  series 
  near 
  Freney. 
  

  

  (o) 
  Calc-mica-schists 
  east 
  of 
  Cottian 
  watershed. 
  

  

  (e) 
  Gneisses, 
  lower 
  part 
  of 
  Val 
  Chisone. 
  

  

  B. 
  Eastern 
  Alps. 
  

  

  (a) 
  Central 
  gneiss 
  (von 
  Hauer), 
  Velber-Tauren 
  district. 
  

   ((3) 
  Mica-schist 
  and 
  Gneiss 
  (von 
  Hauer). 
  

   (y) 
  " 
  Thonglimmerschiefer 
  " 
  series. 
  

  

  Introduction. 
  

  

  In 
  the 
  address 
  which 
  I 
  delivered 
  at 
  the 
  Anniversary 
  Meeting 
  of 
  the 
  

   Society 
  in 
  1886, 
  1 
  gave 
  a 
  brief 
  outline 
  of 
  some 
  investigations 
  into 
  

   the 
  petrology 
  and 
  structure 
  of 
  certain 
  districts 
  of 
  the 
  Oberland, 
  

   Pennine, 
  and 
  Lepontine 
  Alps. 
  These 
  had 
  led 
  me 
  to 
  conclusions 
  

   which 
  were 
  then 
  stated, 
  and 
  had 
  further 
  indicated 
  to 
  me 
  the 
  prin- 
  

   cipal 
  types 
  of 
  rock 
  recognized 
  by 
  the 
  Swiss 
  geologists, 
  and 
  enabled 
  

   me, 
  as 
  it 
  were, 
  to 
  translate 
  into 
  stone 
  one 
  of 
  their 
  maps. 
  I 
  then 
  

   determined 
  to 
  make 
  two 
  traverses 
  of 
  the 
  Alpine 
  chain 
  at 
  distances 
  

   remote 
  from 
  the 
  central 
  portion 
  (the 
  scene 
  of 
  my 
  previous 
  work) 
  

   arid 
  from 
  each 
  othar, 
  so 
  as 
  to 
  acquire 
  a 
  knowledge 
  of 
  the 
  rock-types 
  

   employed 
  in 
  mapping 
  by 
  geologists 
  outside 
  the 
  Swiss 
  Republic, 
  and 
  

   compare 
  the 
  crystalline 
  schists 
  or 
  gneisses 
  of 
  these 
  regions 
  with 
  

   those 
  already 
  known 
  to 
  me. 
  The 
  points, 
  I 
  may 
  again 
  mention, 
  on 
  

   which 
  I 
  was 
  specially 
  seeking 
  for 
  light 
  were 
  (1) 
  the 
  relation 
  of 
  

   foliation 
  to 
  pressure, 
  stratification, 
  &c, 
  or, 
  in 
  other 
  words, 
  the 
  

   history 
  of 
  the 
  genesis 
  of 
  gneisses 
  and 
  schists 
  ; 
  (2) 
  the 
  value 
  of 
  the 
  

   apparent 
  stratigraphical 
  succession 
  which 
  I 
  had 
  observed 
  over 
  a 
  

   considerable 
  district 
  of 
  the 
  Swiss 
  Alps. 
  

  

  f2 
  

  

  