﻿J. 
  W. 
  JUDD 
  ON 
  THE 
  SECONDARY 
  ROCKS 
  OF 
  SCOTLAND. 
  267 
  

  

  In 
  the 
  case 
  of 
  the 
  celebrated 
  Scur 
  of 
  Eigg, 
  however, 
  I 
  believe 
  that 
  

   we 
  have 
  a 
  fragment 
  of 
  a 
  lava 
  stream 
  which 
  proceeded 
  from 
  one 
  of 
  

   these 
  " 
  puys," 
  every 
  other 
  trace 
  of 
  which, 
  however, 
  has 
  been 
  re- 
  

   moved. 
  The 
  character 
  and 
  relations 
  of 
  this 
  interesting 
  mass 
  of 
  rock 
  

   have 
  been 
  very 
  clearly 
  illustrated 
  by 
  Prof. 
  Greikie 
  ; 
  and 
  I 
  would 
  

   only 
  suggest 
  with 
  regard 
  to 
  it 
  that 
  the 
  characters 
  of 
  the 
  buried 
  con- 
  

   glomerate 
  are 
  suggestive 
  of 
  a 
  mountain-ravine 
  subject 
  to 
  the 
  passage 
  

   of 
  violent 
  floods 
  rather 
  than 
  of 
  an 
  ordinary 
  river- 
  channel. 
  It 
  seems 
  

   to 
  me 
  probable 
  that 
  this 
  ravine 
  was 
  situated 
  on 
  the 
  flanks 
  of 
  the 
  

   great 
  volcano 
  of 
  Rum*, 
  then 
  an 
  extinct 
  and 
  rapidly 
  disintegrating 
  

   pile 
  ; 
  that 
  after 
  the 
  accumulation 
  by 
  the 
  flooded 
  stream 
  of 
  fragments 
  

   of 
  all 
  sizes 
  of 
  lava 
  and 
  sandstone 
  (all 
  of 
  which 
  would 
  be 
  naturally 
  

   derived 
  from 
  the 
  ruins 
  of 
  that 
  volcano) 
  and 
  the 
  intermingling 
  with 
  

   these 
  of 
  uprooted 
  trees 
  (the 
  Pinites 
  eggensis) 
  which 
  grew 
  upon 
  its 
  

   slopes, 
  the 
  whole 
  was 
  buried 
  and 
  sealed 
  up 
  in 
  consequence 
  of 
  several 
  

   lava 
  streams, 
  issuing 
  from 
  an 
  (at 
  that 
  time) 
  eruptive 
  " 
  puy," 
  finding 
  

   their 
  way 
  into 
  and 
  filling 
  up 
  the 
  ravine. 
  The 
  course 
  of 
  the 
  subse- 
  

   quent 
  changes 
  was 
  similar 
  to 
  those 
  long 
  ago 
  shown 
  by 
  Mr. 
  Scrope 
  to 
  

   have 
  taken 
  place 
  in 
  so 
  many 
  instances 
  in 
  Auvergne 
  ; 
  and, 
  like 
  these 
  

   latter, 
  they 
  have 
  raised 
  up 
  a 
  striking 
  monument 
  to 
  the 
  power 
  and 
  

   duration 
  of 
  those 
  forces 
  which, 
  almost 
  unnoticed 
  by 
  us, 
  sculpture 
  

   the 
  earth's 
  surface. 
  The 
  history 
  of 
  the 
  events 
  connected 
  with 
  the 
  

   formation 
  of 
  the 
  Scur 
  of 
  Eigg 
  has 
  been 
  very 
  clearly 
  described 
  and 
  

   its 
  lessons 
  eloquently 
  enforced 
  by 
  Prof. 
  Geikie. 
  

  

  13. 
  Subterranean 
  Phenomena 
  of 
  the 
  Tertiary 
  Volcanoes. 
  — 
  In 
  the 
  

   preceding 
  pages 
  it 
  has 
  been 
  my 
  principal 
  object 
  to 
  show 
  that 
  in 
  the 
  

   Hebrides 
  we 
  have 
  evidence, 
  mutilated 
  and 
  fragmentary 
  it 
  may 
  be, 
  

   but 
  nevertheless 
  most 
  clear 
  and 
  unmistakable, 
  of 
  the 
  occurrence 
  of 
  

   a 
  series 
  of 
  phenomena 
  which, 
  alike 
  in 
  their 
  character 
  and 
  their 
  se- 
  

   quence, 
  are 
  identical 
  with 
  those 
  exhibited 
  by 
  existing 
  volcanoes. 
  

   But 
  interesting 
  as 
  these 
  conclusions 
  undoubtedly 
  are, 
  they 
  are 
  

   not 
  perhaps 
  the 
  most 
  important 
  of 
  the 
  fruits 
  of 
  a 
  geological 
  study 
  

   of 
  the 
  beautiful 
  dissected 
  volcanoes 
  of 
  the 
  Highlands. 
  Still 
  more 
  

   suggestive, 
  from 
  the 
  circumstance 
  that 
  they 
  enable 
  us 
  to 
  correlate 
  

   the 
  familiar 
  subaerial 
  actions 
  of 
  volcanoes 
  with 
  others 
  often 
  regarded 
  

   as 
  wholly 
  distinct 
  in 
  character 
  and 
  origin, 
  are 
  the 
  phenomena 
  pre- 
  

   sented 
  to 
  us 
  when 
  we 
  study 
  the 
  connexions 
  between 
  the 
  intrusive 
  

   masses 
  constituting 
  the 
  centres 
  of 
  these 
  ancient 
  volcanic 
  piles, 
  and 
  

   the 
  older 
  stratified 
  rocks 
  through 
  which 
  they 
  rise. 
  To 
  this 
  most 
  

   interesting 
  subject 
  I 
  now 
  proceed 
  to 
  direct 
  attention. 
  

  

  The 
  manner 
  in 
  which 
  the 
  surrounding 
  strata 
  are 
  seen 
  to 
  be 
  up- 
  

   heaved, 
  contorted, 
  and 
  metamorphosed 
  by 
  the 
  great 
  eruptive 
  crys- 
  

   talline 
  masses, 
  whether 
  of 
  acid 
  or 
  basic 
  composition, 
  has 
  been 
  already 
  

   pointed 
  out 
  in 
  a 
  number 
  of 
  different 
  localities. 
  But 
  in 
  the 
  case 
  of 
  

   the 
  island 
  of 
  Skye, 
  it 
  was 
  first 
  shown 
  by 
  Dr. 
  Macculloch, 
  and 
  after- 
  

  

  * 
  As 
  an 
  example 
  of 
  a 
  " 
  puy 
  " 
  in 
  Auvergne, 
  similarly 
  situated 
  to 
  that 
  which 
  

   appears 
  to 
  have 
  given 
  rise 
  to 
  the 
  lavas 
  forming 
  the 
  Scur 
  of 
  Eigg, 
  I 
  may 
  point 
  

   to 
  the 
  Puy 
  de 
  Tartaret, 
  which, 
  rising 
  in 
  the 
  Valley 
  of 
  Chambon, 
  one 
  of 
  the 
  

   great 
  ravines 
  cut 
  on 
  the 
  flanks 
  of 
  Mont 
  Dore, 
  has 
  poured 
  forth 
  a 
  lava 
  stream 
  

   which 
  has 
  occupied 
  all 
  the 
  lower 
  parts 
  of 
  that 
  great 
  watercourse. 
  

  

  