﻿538 
  MAJOB-GEXEKAL 
  C. 
  A. 
  M'ilAHOX 
  OX 
  THE 
  HORXBLEXDE-SCHTSTS 
  

  

  zine,' 
  has 
  given 
  a 
  photograph 
  of 
  a 
  portion 
  of 
  an 
  intrusive 
  vein 
  in 
  a 
  

   cliff 
  at 
  Pen 
  Voose. 
  As 
  I 
  desire 
  to 
  note 
  one 
  or 
  two 
  important 
  facts 
  

   not 
  heretofore 
  brought 
  to 
  notice 
  regarding 
  this 
  vein, 
  I 
  give 
  a 
  rough 
  

   sketch 
  of 
  it 
  below. 
  The 
  veins 
  shown 
  at 
  e 
  e 
  e 
  are 
  very 
  thin 
  and 
  very 
  

   numerous*. 
  The 
  " 
  granulite 
  " 
  here 
  is 
  a 
  holo 
  crystalline 
  diorite, 
  but 
  I 
  

   was 
  not 
  able 
  to 
  discover 
  any 
  break 
  between 
  it 
  and 
  the 
  rocks 
  of 
  the 
  

   " 
  granulitic 
  " 
  group 
  which 
  show 
  in 
  force 
  in 
  this 
  cove. 
  

  

  I 
  may 
  observe 
  in 
  passing 
  that 
  the 
  granite 
  is 
  distinctly 
  foliated 
  at 
  

   A 
  1 
  , 
  but 
  the 
  foliation 
  dies 
  out 
  towards 
  A 
  2 
  . 
  The 
  direction 
  of 
  the 
  

   foliation 
  is 
  indicated 
  by 
  a 
  double 
  arrow. 
  Some 
  of 
  the 
  fine 
  veins 
  

   are 
  also 
  foliated, 
  the 
  foliation 
  being 
  parallel 
  to 
  their 
  sides. 
  Now 
  

   the 
  point 
  to 
  be 
  noted 
  is 
  that 
  the 
  dioritic 
  rock 
  (B 
  1 
  , 
  B) 
  and 
  the 
  gabbro 
  

  

  Fig. 
  11. 
  — 
  Intrusive 
  Vein 
  in 
  Cliff 
  at 
  Pen 
  Voose. 
  

  

  at 
  D 
  give 
  no 
  indication 
  of 
  foliation 
  either 
  in 
  the 
  field 
  or 
  under 
  the 
  

   microscope. 
  I 
  have 
  examined 
  specimens 
  of 
  the 
  granite 
  taken 
  from 
  

   a. 
  and 
  of 
  the 
  diorite 
  taken 
  from 
  the 
  point 
  marked 
  6 
  — 
  the 
  places 
  

   being 
  only 
  a 
  few 
  inches 
  apart 
  — 
  but 
  though 
  the 
  granite 
  is 
  very 
  dis- 
  

   tinctly 
  foliated, 
  the 
  diorite 
  does 
  not 
  show 
  the 
  slightest 
  trace 
  of 
  this 
  

   structure 
  f. 
  This 
  fact 
  has, 
  I 
  think, 
  an 
  important 
  bearing 
  on 
  the 
  

   question 
  of 
  the 
  foliation 
  of 
  the 
  Lizard 
  rocks. 
  We 
  need 
  not 
  go 
  

   further 
  than 
  the 
  Lizard 
  to 
  learn 
  that 
  diorite 
  and 
  gabbro 
  put 
  on 
  

   foliation 
  with 
  great 
  ease 
  — 
  more 
  readily, 
  probably, 
  or 
  at 
  any 
  rate 
  as 
  

   readily, 
  as 
  granite 
  — 
  and 
  that 
  being 
  so 
  the 
  fact 
  that 
  the 
  granite 
  is 
  

   foliated, 
  but 
  the 
  diorite 
  and 
  gabbro 
  on 
  either 
  side 
  of 
  it 
  are 
  not 
  foliated, 
  

   seems 
  to 
  me 
  to 
  lead 
  to 
  the 
  unavoidable 
  conclusion 
  that 
  the 
  foliation 
  

   of 
  the 
  granite 
  was 
  produced 
  prior 
  to 
  its 
  perfect 
  consolidation. 
  The 
  

   granite 
  was 
  the 
  last 
  of 
  the 
  three 
  eruptive 
  rocks 
  to 
  appear, 
  and 
  had 
  

  

  * 
  The 
  exigencies 
  of 
  a 
  small 
  woodcut 
  necessitated 
  their 
  being 
  reduced 
  in 
  num- 
  

   ber 
  and 
  increased 
  in 
  relative 
  thickness. 
  

  

  + 
  The 
  foliated 
  granite 
  alluded 
  to 
  will 
  be 
  found 
  under 
  Xos. 
  20, 
  21 
  of 
  the 
  " 
  gra- 
  

   nulitic 
  " 
  group 
  table 
  (p. 
  532), 
  and 
  the 
  diorite 
  taken 
  from 
  (b) 
  under 
  No. 
  12 
  of 
  

   the 
  same 
  list. 
  

  

  