﻿536 
  MAJOE-GENEEAE 
  C. 
  A. 
  M'MAHOX 
  OX 
  THE 
  HOEXBLEXDE-SCHISTS 
  

  

  of 
  regular 
  banding. 
  For 
  instance, 
  I 
  observed 
  near 
  the 
  Lion 
  Rock 
  

   a 
  jutting 
  cliff 
  of 
  the 
  " 
  granulitic 
  " 
  group 
  injected 
  in 
  the 
  usual 
  way 
  

   with 
  numerous 
  granite-veins 
  on 
  one 
  of 
  its 
  sides, 
  none 
  of 
  the 
  quasi- 
  

   bands, 
  however, 
  intruding 
  so 
  far 
  as 
  the 
  opposite 
  side 
  of 
  the 
  rock. 
  

   The 
  same 
  thing 
  may 
  even 
  be 
  seen 
  in 
  one 
  of 
  my 
  hand-specimens. 
  

   In 
  the 
  latter 
  only 
  the 
  strongest 
  of 
  the 
  veins 
  have 
  penetrated 
  right 
  

   through 
  the 
  substance 
  of 
  the 
  specimen 
  from 
  side 
  to 
  side. 
  This 
  

   condition 
  of 
  things 
  is 
  exactly 
  what 
  might 
  be 
  anticipated 
  on 
  the 
  

   hypothesis 
  of 
  injection 
  : 
  for 
  at 
  a 
  certain 
  distance 
  from 
  the 
  focus 
  of 
  

   injection, 
  which 
  would 
  vary 
  in 
  each 
  case 
  with 
  the 
  force 
  of 
  propulsion, 
  

   we 
  should 
  expect 
  to 
  find 
  that 
  the 
  resistance 
  offered 
  by 
  the 
  dioritic 
  

   rock 
  would 
  overcome 
  the 
  piercing 
  power 
  of 
  the 
  granite. 
  

  

  The 
  process 
  of 
  injection 
  was 
  doubtless 
  aided 
  by 
  the 
  partial 
  plasti- 
  

   city 
  of 
  the 
  dioritic 
  rocks 
  — 
  a 
  plasticity 
  induced 
  probably 
  by 
  the 
  

   neighbourhood 
  of 
  igneous 
  masses, 
  for 
  it 
  seems 
  to 
  have 
  been 
  local 
  in 
  

   its 
  development. 
  It 
  would 
  also 
  have 
  been 
  aided 
  in 
  the 
  case 
  of 
  

   consolidated 
  ash-beds 
  — 
  especially 
  in 
  submarine 
  ash-beds 
  — 
  by 
  the 
  

   planes 
  of 
  sedimentation, 
  and 
  in 
  the 
  case 
  of 
  diorite 
  intruded 
  as 
  sheets 
  

   by 
  the 
  foliation 
  developed 
  in 
  a 
  direction 
  parallel 
  to 
  the 
  bedding. 
  

   The 
  existence 
  of 
  such 
  planes 
  of 
  weakness 
  would 
  explain 
  why 
  the 
  

   injected 
  granite 
  displayed 
  a 
  tendency 
  to 
  follow 
  lines 
  parallel 
  to 
  the 
  

   bedding, 
  and 
  in 
  doing 
  so 
  produced 
  the 
  superficial 
  appearance 
  of 
  

   banding. 
  

  

  The 
  remarks 
  offered 
  under 
  the 
  head 
  of 
  hornblende-schists 
  on 
  the 
  

   application 
  of 
  the 
  hypothesis 
  of 
  deformation 
  to 
  the 
  explanation 
  of 
  

   the 
  fine 
  banding 
  of 
  those 
  rocks 
  apply 
  generally 
  to 
  the 
  banding 
  of 
  the 
  

   " 
  granulitic" 
  series 
  and 
  need 
  not 
  be 
  repeated. 
  Suffice 
  it 
  to 
  say 
  that 
  

   I 
  have 
  not 
  observed 
  anything 
  in 
  the 
  microscopic 
  structure 
  of 
  the 
  

   rocks 
  under 
  description 
  to 
  support 
  the 
  application 
  of 
  the 
  deformation- 
  

   hypothesis 
  to 
  the 
  " 
  granulitic 
  * 
  group. 
  The 
  quasi-banding 
  described 
  

   is 
  consistent 
  with 
  the 
  theory 
  of 
  injection; 
  but 
  I 
  do 
  not 
  see 
  that 
  it 
  

   can 
  be 
  reasonably 
  accounted 
  for 
  by 
  any 
  process 
  of 
  deformation. 
  

  

  Figs. 
  8 
  and 
  9 
  are 
  woodcuts 
  of 
  two 
  hand-specimens 
  from 
  Kildown 
  

   Cove 
  *. 
  Had 
  I 
  been 
  able 
  to 
  take 
  photographs 
  of 
  rucks 
  in 
  situ, 
  more 
  

   striking 
  illustrations 
  might 
  have 
  been 
  given, 
  but 
  figs. 
  8 
  and 
  9 
  may 
  

   be 
  accepted 
  as 
  fair 
  samples 
  of 
  the 
  structure 
  under 
  description. 
  

  

  In 
  the 
  case 
  of 
  injections 
  into 
  the 
  porphyritic 
  diorite 
  the 
  thin 
  veins 
  

   of 
  granite 
  are 
  deflected 
  from 
  their 
  course 
  by 
  the 
  porphyritic 
  

   crystals. 
  In 
  one 
  instance 
  I 
  found 
  that 
  the 
  felspar 
  that 
  had 
  deflected 
  

   a 
  vein 
  was 
  about 
  three 
  inches 
  long, 
  and 
  it 
  was 
  orientated 
  nearly 
  at 
  

   right 
  angles 
  to 
  the 
  vein 
  (as 
  shown 
  in 
  fig. 
  10), 
  an 
  incidental 
  proof, 
  

   it 
  seems 
  to 
  me, 
  that 
  the 
  veining 
  was 
  not 
  produced 
  by 
  dynamic 
  

   deformation. 
  The 
  shearing 
  or 
  crushing 
  that 
  could 
  have 
  reduced 
  a 
  

   lump 
  of 
  granite 
  to 
  an 
  attenuated 
  string 
  would 
  have 
  crushed 
  the 
  

   felspar 
  to 
  a 
  flat 
  wafer. 
  

  

  Air. 
  Teall, 
  in 
  his 
  paper 
  already 
  quoted 
  from 
  the 
  ' 
  Geological 
  Maga- 
  

  

  * 
  One 
  of 
  these 
  illustrations 
  was 
  photographed 
  on 
  the 
  block 
  ; 
  in 
  the 
  case 
  of 
  

   the 
  other 
  this 
  process 
  could 
  not 
  be 
  employed, 
  owing 
  to 
  the 
  red 
  tint 
  of 
  the 
  

   granitic 
  veins. 
  

  

  