﻿J. 
  W. 
  JTJDD 
  OK 
  THE 
  SECONDARY 
  ROCEU 
  Of 
  SCOTLAND. 
  255 
  

  

  and 
  are 
  traversed 
  by 
  numerous 
  " 
  contemporaneous 
  veins," 
  usually 
  of 
  

   similar 
  composition 
  to 
  the 
  mass 
  which 
  they 
  traverse 
  ; 
  the 
  gabbros 
  of 
  

   the 
  Cuchullin 
  Hills 
  and 
  Blabheinn 
  pass 
  insensibly 
  into 
  dolerites 
  and 
  

   basalts, 
  and 
  are 
  also 
  traversed 
  by 
  many 
  " 
  contemporaneous 
  veins." 
  

   Both 
  of 
  these 
  intrusive 
  rocks, 
  in 
  places, 
  exhibit 
  the 
  pseudo-stratified 
  

   appearances 
  so 
  commonly 
  displayed 
  by 
  igneous 
  masses. 
  

  

  That 
  the 
  rocks 
  of 
  basic 
  composition 
  were 
  ejected 
  subsequently 
  to 
  

   those 
  of 
  the 
  acid 
  variety, 
  is 
  illustrated 
  by 
  sections 
  at 
  a 
  number 
  of 
  

   different 
  points 
  ; 
  and 
  this 
  fact 
  was 
  deteeted 
  by 
  the 
  late 
  Principal 
  

   J. 
  D. 
  Forbes 
  * 
  in 
  1845, 
  and 
  by 
  Professor 
  Zirkelf 
  in 
  18 
  68-. 
  

  

  As 
  in 
  Rum, 
  the 
  ejected 
  rocks, 
  lavas, 
  agglomerates, 
  and 
  breccias 
  

   form 
  only 
  disconnected 
  outliers 
  in 
  Skye 
  ; 
  but 
  some 
  of 
  these 
  present 
  

   very 
  interesting 
  characters. 
  Patches 
  of 
  volcanic 
  agglomerates 
  and 
  

   breccias, 
  including 
  fragments 
  of 
  the 
  several 
  Primary 
  and 
  Secondary 
  

   rocks 
  through 
  which 
  this 
  volcano 
  has 
  burst, 
  are 
  found 
  at 
  several 
  

   points: 
  the 
  preservation 
  of 
  these 
  is 
  probably 
  due 
  to 
  local 
  subsidences; 
  

   and 
  a 
  good 
  example 
  of 
  them 
  may 
  be 
  examined 
  in 
  the 
  hill 
  on 
  the 
  

   south 
  of 
  Beinn 
  Dearg, 
  known 
  as 
  Cnoc-na-Fitheach. 
  Outliers 
  of 
  

   the 
  felstone 
  lavas, 
  more 
  or 
  less 
  mingled 
  withscorise 
  and 
  ashes, 
  occur 
  

   at 
  a 
  number 
  of 
  points 
  round 
  the 
  central 
  mountain-group, 
  and. 
  i& 
  

   the 
  island 
  of 
  Scalpa 
  and 
  the 
  peninsula 
  of 
  Strathaird 
  are 
  seen 
  lying 
  

   directly 
  upon 
  the 
  various 
  Primary 
  and 
  Secondary 
  strata. 
  

  

  Of 
  the 
  great 
  basaltic 
  plateaux 
  which 
  doubtless 
  once 
  surrounded 
  

   the 
  old 
  volcano 
  of 
  Skye 
  on 
  all 
  sides, 
  we 
  have 
  also 
  only 
  a 
  number 
  of 
  

   fragments 
  left. 
  By 
  fur 
  the 
  largest 
  and 
  most 
  important 
  of 
  these 
  i&. 
  

   the 
  one 
  which, 
  stretching 
  north-Avestwards, 
  constitutes 
  the 
  great 
  

   peninsulas 
  of 
  Trotternish, 
  Vaternish, 
  Durinish, 
  and 
  Minginish. 
  This, 
  

   mass 
  of 
  lavas 
  has 
  been 
  upheaved 
  on 
  its 
  eastern 
  side 
  so 
  as 
  to 
  display 
  

   in 
  a 
  very 
  interesting 
  manner 
  the 
  Secondary 
  rocks 
  upon 
  which 
  it. 
  

   lies. 
  Another 
  small 
  outlier 
  of 
  the 
  basaltic 
  plateaux, 
  which 
  has. 
  

   escaped 
  from 
  destruction 
  by 
  denudation, 
  occurs 
  in 
  the 
  adjacent 
  

   island 
  of 
  Raasay, 
  where 
  it 
  forms 
  the 
  highest 
  point, 
  the 
  striking 
  hill 
  

   of 
  Dun 
  Can. 
  In 
  Applecross, 
  however, 
  denudation 
  has 
  proceeded; 
  

   one 
  step 
  further, 
  the 
  lava 
  streams 
  having 
  been 
  altogether 
  removed,, 
  

   and 
  thus 
  the 
  Secondary 
  rocks 
  with 
  their 
  included 
  sheets 
  of 
  intrusive 
  

   igneous 
  rock 
  exposed 
  at 
  the 
  surface. 
  .Further, 
  for 
  great 
  dis- 
  

   tances 
  round 
  the 
  central 
  mountain-group 
  of 
  Skye 
  the 
  whole 
  of 
  the 
  

   stratified 
  rocks 
  are 
  penetrated 
  by 
  innumerable 
  dykes 
  and 
  intrusive 
  

   masses 
  both 
  of 
  acid 
  and 
  basic 
  composition. 
  

  

  9. 
  The 
  Volcano 
  of 
  St. 
  Kilda. 
  — 
  I 
  have 
  not 
  yet 
  been 
  able 
  to 
  visit 
  

   this 
  remote 
  group 
  of 
  islands 
  ; 
  but 
  from 
  the 
  descriptions 
  of 
  Martin 
  

   and 
  Macculloch 
  it 
  is 
  sufficiently 
  obvious 
  that 
  we 
  have 
  in 
  them 
  the 
  

   relics 
  of 
  another 
  of 
  the 
  old 
  Tertiary 
  volcanoes. 
  The 
  islands 
  are 
  said 
  

   to 
  consist 
  wholly 
  of 
  "trap-rocks 
  ; 
  " 
  and 
  the 
  central 
  and 
  largest 
  of 
  the 
  

   group 
  is 
  described 
  as 
  being 
  formed 
  in 
  its 
  eastern 
  part 
  of 
  granite, 
  and 
  

   in 
  its 
  western 
  part 
  of 
  gabbro. 
  Macculloch, 
  who 
  was 
  so 
  competent 
  

   a 
  judge 
  of 
  petrological 
  characters, 
  informs 
  us 
  that 
  these 
  rocks 
  were 
  

   identical 
  in 
  every 
  respect 
  with 
  those 
  found 
  in 
  the 
  island 
  of 
  Bum. 
  

  

  * 
  Edinb. 
  New 
  Phil. 
  Journ. 
  New 
  Ser. 
  vol. 
  xl. 
  (1845-46), 
  p. 
  86. 
  

  

  t 
  Zeitschr 
  d. 
  deutschen 
  geologischen 
  Gesellschaft, 
  Jahrg. 
  1871, 
  p. 
  90. 
  

  

  