﻿188 
  PROF. 
  J. 
  W. 
  JTTDD 
  ON 
  THE 
  TERTIARY 
  VOLCANOES 
  

  

  stone 
  and 
  the 
  Glacial 
  deposits. 
  Of 
  these 
  formations, 
  it 
  may 
  be 
  

   remembered 
  that 
  the 
  strata 
  of 
  Carboniferous 
  and 
  Cretaceous 
  age 
  

   had 
  remained 
  wholly 
  unrecognized 
  before 
  my 
  studies 
  commenced 
  ; 
  

   while, 
  with 
  respect 
  to 
  the 
  age 
  and 
  relations 
  of 
  the 
  several 
  members 
  

   of 
  the 
  Triassic 
  and 
  Jurassic 
  systems, 
  as 
  well 
  as 
  concerning 
  the 
  great 
  

   masses 
  of 
  igneous 
  rocks, 
  very 
  confused 
  and 
  inaccurate 
  ideas 
  prevailed. 
  

   I 
  may 
  add 
  that 
  the 
  country 
  in 
  which 
  these 
  rocks 
  are 
  exhibited 
  was 
  

   at 
  the 
  time 
  quite 
  destitute 
  of 
  any 
  reliable 
  maps 
  upon 
  which 
  the 
  

   observations 
  of 
  the 
  geologist 
  could 
  be 
  accurately 
  recorded. 
  Under 
  

   these 
  circumstances, 
  I 
  may 
  claim 
  that 
  my 
  work 
  should 
  be 
  judged, 
  

   I 
  will 
  not 
  say 
  with 
  indulgence 
  — 
  for 
  such 
  I 
  do 
  not 
  ask 
  — 
  but 
  with 
  

   that 
  fair 
  consideration 
  which 
  pioneer 
  labour 
  in 
  our 
  science 
  has 
  

   always 
  received 
  at 
  the 
  hands 
  of 
  those 
  who 
  constitute 
  this 
  Society. 
  

   If 
  the 
  great 
  outlines 
  of 
  the 
  subject 
  were 
  faithfully 
  traced, 
  and 
  the 
  

   true 
  bearings 
  of 
  the 
  leading 
  facts 
  were 
  rightly 
  appreciated, 
  I 
  submit 
  

   that 
  this 
  was 
  all 
  that 
  could 
  be 
  expected 
  under 
  the 
  circumstances, 
  as 
  

   it 
  was 
  certainly 
  all 
  that 
  I 
  hoped 
  to 
  be 
  able 
  to 
  accomplish. 
  

  

  During 
  the 
  last 
  fifteen 
  years 
  it 
  has 
  been 
  my 
  endeavour 
  to 
  fill 
  in 
  the 
  

   sketch, 
  of 
  which 
  the 
  outlines 
  had, 
  I 
  believe, 
  been 
  accurately 
  drawn, 
  

   and 
  to 
  correct 
  or 
  supplement 
  those 
  points 
  of 
  detail 
  upon 
  which 
  my 
  

   information 
  was 
  defective 
  ; 
  and 
  I 
  trust 
  that, 
  in 
  doing 
  so, 
  I 
  have 
  

   shown 
  no 
  reluctance 
  to 
  confess 
  omissions 
  or 
  mistakes 
  of 
  which 
  I 
  

   may 
  have 
  been 
  guilty. 
  

  

  My 
  original 
  intention 
  had 
  been 
  to 
  confine 
  the 
  series 
  of 
  memoirs 
  on 
  

   " 
  The 
  Secondary 
  Eocks 
  of 
  Scotland 
  " 
  to 
  the 
  description 
  of 
  the 
  strati- 
  

   fied 
  deposits 
  ; 
  but 
  when 
  I 
  came 
  to 
  study 
  the 
  relations 
  of 
  these 
  to 
  the 
  

   igneous 
  masses 
  in 
  the 
  Western 
  Isles 
  of 
  Scotland, 
  I 
  found 
  that 
  such 
  

   very 
  serious 
  errors 
  had 
  been 
  made 
  in 
  the 
  interpretation 
  of 
  the 
  latter, 
  

   as 
  to 
  necessitate 
  the 
  preparation 
  of 
  a 
  general 
  sketch 
  of 
  what 
  appeared 
  

   to 
  me 
  to 
  be 
  their 
  true 
  relations. 
  In 
  justification 
  of 
  this 
  course, 
  I 
  

   am 
  compelled, 
  in 
  consequence 
  of 
  statements 
  that 
  have 
  recently 
  

   been 
  made, 
  to 
  refer 
  to 
  the 
  literature 
  bearing 
  upon 
  the 
  subject 
  which 
  

   was 
  in 
  existence 
  when 
  I 
  commenced 
  my 
  task 
  in 
  1871. 
  

  

  II. 
  Views 
  which 
  were 
  maintained 
  previous 
  to 
  1874. 
  

  

  The 
  very 
  able 
  geologist, 
  mineralogist, 
  and 
  chemist, 
  Dr. 
  John 
  

   Macculloch, 
  early 
  in 
  the 
  present 
  century, 
  gave 
  a 
  most 
  admirable 
  

   account 
  of 
  the 
  igneous 
  rocks 
  of 
  the 
  "Western 
  Isles 
  of 
  Scotland. 
  He 
  

   clearly 
  perceived 
  and 
  distinctly 
  pointed 
  out 
  the 
  fact 
  that 
  the 
  granites 
  

   and 
  gabbros 
  of 
  the 
  area 
  constitute, 
  with 
  the 
  felsites 
  and 
  basalts, 
  one 
  

   great 
  contemporaneous 
  series 
  of 
  rocks 
  — 
  a 
  series 
  which, 
  as 
  a 
  whole, 
  

   overlies 
  and 
  is 
  younger 
  than 
  the 
  Secondary 
  strata 
  of 
  the 
  district. 
  

   He 
  noticed 
  the 
  apparent 
  interbedding 
  of 
  these 
  igneous 
  rocks 
  with 
  

   Oolitic 
  and 
  Liassic 
  strata 
  ; 
  but 
  he 
  clearly 
  demonstrated 
  that 
  in 
  all 
  

   such 
  cases 
  the 
  igneous 
  masses 
  are 
  really 
  intrusive 
  in, 
  and 
  therefore 
  

   younger 
  than, 
  the 
  Jurassic 
  rocks 
  *. 
  

  

  * 
  Macculloch's 
  observations 
  were 
  published 
  in 
  the 
  First 
  Series 
  of 
  Transac- 
  

   tions 
  of 
  this 
  Society, 
  and 
  afterwards 
  in 
  fuller 
  detail 
  in 
  Ins 
  classic 
  ' 
  Description 
  

   of 
  the 
  Western 
  Isles 
  of 
  Scotland,' 
  3 
  vols, 
  with 
  plates 
  and 
  maps 
  (1819). 
  

  

  