﻿68 
  PROF. 
  T. 
  G. 
  BONTTEr 
  ON" 
  TWO 
  TRAVERSES 
  OP 
  THE 
  

  

  For 
  these 
  purposes 
  it 
  was 
  requisite 
  that 
  any 
  section 
  examined 
  

   should 
  fulfil, 
  as 
  nearly 
  as 
  possible, 
  the 
  following 
  conditions 
  : 
  — 
  

  

  (1) 
  It 
  should 
  run 
  in 
  a 
  fairly 
  straight 
  line 
  as 
  nearly 
  as 
  might 
  

   be 
  at 
  right 
  angles 
  to 
  the 
  apparent 
  strike 
  of 
  the 
  rocks. 
  

  

  (2) 
  It 
  should 
  exhibit 
  a 
  seeming 
  succession 
  as 
  extensive 
  as 
  pos- 
  

   sible. 
  

  

  (3) 
  It 
  should 
  avoid, 
  as 
  far 
  as 
  possible, 
  snowfields, 
  glaciers, 
  alps, 
  

   and 
  cultivated 
  lands, 
  so 
  as 
  to 
  exhibit 
  fairly 
  continuous 
  exposures 
  

   of 
  rock 
  in 
  situ. 
  

  

  (4) 
  Travel 
  should 
  not 
  be 
  difficult. 
  

  

  These 
  conditions 
  are 
  usually 
  best 
  satisfied 
  by 
  ascending 
  valleys 
  

   rather 
  than 
  ridges, 
  and 
  crossing 
  passes 
  of 
  moderate 
  elevation. 
  

  

  My 
  Alpine 
  wanderings 
  during 
  the 
  last 
  seven-and-twenty 
  years 
  

   had 
  given 
  me 
  a 
  general 
  knowledge 
  of 
  the 
  geology 
  of 
  the 
  whole 
  

   region 
  from 
  the 
  Yiso 
  to 
  the 
  Glockner, 
  and, 
  after 
  a 
  careful 
  considera- 
  

   tion 
  of 
  the 
  question, 
  and 
  consultation 
  with 
  my 
  friend 
  the 
  Rev. 
  E. 
  Hill, 
  

   who 
  had 
  again 
  promised 
  to 
  give 
  me 
  the 
  pleasure 
  of 
  his 
  society 
  and 
  

   the 
  advantage 
  of 
  his 
  cooperation, 
  we 
  decided 
  to 
  take 
  the 
  one 
  section 
  

   between 
  Grenoble 
  and 
  Turin, 
  and 
  the 
  other 
  slightly 
  west 
  of 
  the 
  

   Glockner 
  from 
  the 
  Pusterthal 
  northwards. 
  The 
  former 
  section 
  

   was, 
  indeed, 
  open 
  to 
  some 
  objection, 
  for 
  I 
  knew 
  that 
  the 
  northern 
  

   part 
  of 
  the 
  Dauphine 
  massif 
  was 
  rather 
  monotonous, 
  petrologically 
  

   speaking, 
  in 
  its 
  character, 
  and 
  that 
  a 
  great 
  infold 
  of 
  later 
  Palaeozoic 
  

   and 
  Mesozoic 
  rock 
  occurred 
  at 
  the 
  head 
  of 
  the 
  Durance 
  valley, 
  just 
  

   where 
  an 
  exposure 
  of 
  the 
  crystalline 
  series 
  was 
  particularly 
  de- 
  

   sirable. 
  But 
  I 
  also 
  knew 
  that 
  any 
  line 
  of 
  section, 
  either 
  north 
  or 
  

   south 
  of 
  the 
  glens 
  traversed 
  by 
  the 
  highroad 
  of 
  the 
  Lautaret, 
  would 
  

   have 
  drawbacks 
  no 
  less 
  serious, 
  while 
  in 
  this 
  there 
  were 
  several 
  

   compensatory 
  advantages. 
  

  

  The 
  section 
  of 
  the 
  Eastern 
  Alps 
  obviously 
  fulfilled 
  all 
  our 
  condi- 
  

   tions, 
  for 
  it 
  lay 
  well 
  to 
  the 
  east 
  of 
  the 
  Tyrol, 
  and 
  crossed 
  all 
  the 
  

   principal 
  types 
  indicated 
  by 
  colours 
  in 
  Yon 
  Hauer's 
  map. 
  These 
  

   once 
  learnt, 
  it 
  became 
  easy 
  to 
  connect 
  with 
  Switzerland 
  through 
  

   the 
  G-raubiinden 
  region, 
  which 
  was 
  to 
  some 
  extent 
  included 
  in 
  the 
  

   maps 
  of 
  both 
  countries. 
  

  

  Our 
  study 
  of 
  the 
  Alps, 
  of 
  course, 
  has 
  been 
  comparatively 
  super- 
  

   ficial. 
  Such 
  an 
  admission 
  in 
  these 
  days 
  of 
  careful 
  surveying 
  and 
  

   elaborate 
  petrographical 
  investigation 
  may, 
  at 
  first 
  sight, 
  seem 
  to 
  be 
  

   a 
  sufficient 
  condemnation. 
  But 
  I 
  have 
  seen 
  enough 
  of 
  both 
  methods 
  

   of 
  working 
  to 
  know 
  that 
  each 
  has 
  its 
  place, 
  and, 
  further, 
  that 
  for 
  

   my 
  special 
  purpose 
  a 
  minute 
  research 
  would 
  be 
  of 
  little 
  avail, 
  pos- 
  

   sibly 
  of 
  some 
  harm. 
  The 
  naturalist 
  who 
  stopped 
  to 
  elaborate 
  a 
  

   memoir 
  on 
  the 
  orchids, 
  would 
  probably 
  fail 
  to 
  give 
  us 
  a 
  good 
  idea 
  

   of 
  a 
  South- 
  American 
  forest 
  ; 
  nay, 
  might 
  even 
  persuade 
  himself 
  that 
  

   its 
  vegetation 
  consisted 
  mainly 
  of 
  epiphytes. 
  Hence 
  it 
  has 
  been 
  

   my 
  endeavour 
  in 
  the 
  Alps 
  to 
  become 
  familiar 
  with 
  as 
  large 
  a 
  series 
  

   of 
  rocks 
  as 
  possible, 
  though 
  neither 
  time 
  nor 
  pains 
  has 
  been 
  spared 
  

   in 
  working 
  out 
  details 
  when 
  these 
  promised 
  to 
  throw 
  light 
  on 
  the 
  

   origin 
  of 
  a 
  rock 
  or 
  the 
  history 
  of 
  its 
  structures. 
  Extensive 
  col- 
  

   lections 
  were 
  out 
  of 
  the 
  question, 
  owing 
  to 
  the 
  trouble 
  and 
  expense 
  

  

  