﻿AND 
  BANDED 
  CRYSTALLINE 
  ROCKS 
  OF 
  THE 
  LIZARD. 
  541 
  

  

  the 
  Lion 
  Rock, 
  near 
  the 
  month 
  of 
  Penzance 
  Cove. 
  No 
  one, 
  I 
  may 
  

   say, 
  should 
  attempt 
  to 
  visit 
  this 
  spot 
  without 
  a 
  competent 
  guide, 
  

   for 
  the 
  ground 
  is 
  laborious 
  and 
  somewhat 
  difficult 
  to 
  get 
  over 
  : 
  the 
  

   cliffs 
  are 
  not 
  to 
  be 
  scaled 
  ; 
  and 
  a 
  stranger 
  might 
  run 
  considerable 
  

   danger 
  of 
  being 
  cut 
  off 
  by 
  the 
  tide. 
  

  

  The 
  " 
  granulitic 
  " 
  group 
  is 
  well 
  seen 
  in 
  this 
  neighbourhood, 
  and 
  

   a 
  study 
  of 
  it 
  here 
  is 
  sufficient 
  to 
  show 
  that 
  the 
  quasi-banding 
  seen 
  

   in 
  it 
  (which 
  closely 
  resembles 
  that 
  of 
  the 
  normal 
  " 
  granulite 
  ") 
  is 
  due 
  

   to 
  the 
  injection 
  of 
  granite. 
  Under 
  Yellow 
  Carn, 
  about 
  160 
  yards 
  

   from 
  the 
  Lion 
  Rock, 
  a 
  dioritic 
  rock 
  tarns 
  sharp 
  up 
  the 
  cliff 
  and 
  

   apparently 
  emanates 
  from 
  the 
  " 
  granulitic 
  " 
  rocks 
  seen 
  hard 
  by 
  

   (the 
  actual 
  junction 
  is, 
  I 
  believe, 
  masked 
  by 
  huge 
  boulders). 
  This 
  

   dyke-like 
  mass 
  appeared 
  to 
  me 
  to 
  be 
  a 
  dioritic 
  portion 
  of 
  the 
  

   " 
  granulitic" 
  group, 
  nipped 
  between 
  two 
  converging 
  masses 
  of 
  

   intrusive 
  serpentine 
  ; 
  but 
  it 
  is 
  important 
  to 
  observe 
  that 
  the 
  dio- 
  

   ritic 
  rock 
  does 
  not 
  exhibit 
  banding. 
  Near 
  the 
  junction 
  of 
  this 
  dioritic 
  

   rock 
  and 
  the 
  serpentine 
  I 
  observed 
  several 
  lumps 
  of 
  serpentine 
  that 
  

   looked 
  like 
  truncated 
  tongues. 
  Two 
  of 
  these 
  1 
  was 
  able 
  to 
  trace 
  up 
  

   to 
  within 
  half 
  an 
  inch 
  of 
  the 
  serpentine, 
  from 
  which 
  they 
  were 
  sepa- 
  

   rated 
  by 
  a 
  vein 
  of 
  fibrous 
  serpentine 
  which, 
  to 
  all 
  appearance, 
  has 
  

   been 
  formed 
  by 
  infiltration 
  along 
  a 
  joint. 
  There 
  is, 
  however, 
  so 
  

   much 
  difficulty 
  in 
  distinguishing 
  between 
  an 
  intrusive 
  diorite 
  (when 
  

   non-porphyritic) 
  and 
  dioritic 
  portions 
  of 
  the 
  " 
  granulitic 
  " 
  group 
  

   that 
  I 
  could 
  not 
  feel 
  certain 
  whether 
  these 
  lumps 
  of 
  serpentine 
  were 
  

   tongues 
  or 
  blocks. 
  

  

  Similar 
  blocks 
  occur 
  in 
  the 
  banded 
  series 
  on 
  the 
  east 
  coast, 
  

   about 
  200 
  yards 
  north 
  of 
  the 
  Cavouga 
  rocks. 
  Here 
  the 
  banding 
  

   is, 
  on 
  the 
  whole, 
  more 
  regular 
  than 
  usual, 
  but 
  the 
  dioritic 
  portion 
  

   appears 
  to 
  consist 
  wholly 
  of 
  the 
  porphyritic 
  diorite. 
  The 
  porphy- 
  

   ritic 
  crystals 
  are 
  small, 
  but 
  they 
  are 
  pretty 
  generally 
  disseminated 
  

   through 
  it. 
  The 
  blocks 
  of 
  serpentine 
  alluded 
  to 
  are 
  to 
  be 
  observed 
  

   in 
  this 
  diorite 
  next 
  a 
  mass 
  of 
  serpentine 
  ; 
  they 
  vary 
  in 
  distance 
  

   from 
  it 
  from 
  two 
  inches 
  to 
  two 
  feet, 
  and 
  I 
  could 
  find 
  no 
  instance 
  

   in 
  which 
  they 
  are 
  actually 
  connected 
  with 
  it. 
  We 
  have 
  already 
  seen 
  

   that 
  the 
  porphyritic 
  diorite 
  gives 
  evidence 
  at 
  Polpeor 
  and 
  elsewhere 
  

   of 
  being 
  a 
  truly 
  intrusive 
  rock. 
  Within 
  a 
  few 
  yards 
  of 
  these 
  blocks 
  

   of 
  serpentine 
  in 
  the 
  porphyritic 
  diorite 
  the 
  latter 
  appears 
  as 
  an 
  

   intruder 
  in 
  the 
  serpentine 
  *, 
  and 
  the 
  conclusion 
  seems 
  inevitable 
  that 
  

   here, 
  at 
  all 
  events, 
  the 
  blocks 
  of 
  serpentine 
  are 
  not 
  truncated 
  veins, 
  

   but 
  are 
  true 
  inclusions 
  in 
  eruptive 
  diorite. 
  Tt 
  is 
  material 
  to 
  note 
  

   further 
  that 
  the 
  thin 
  bands 
  of 
  granitic 
  matter 
  in 
  the 
  diorite 
  are 
  bent 
  

   at 
  their 
  points 
  of 
  contact 
  with 
  these 
  boulders. 
  This 
  seems 
  to 
  be 
  

   quite 
  analogous 
  to 
  the 
  cases, 
  mentioned 
  in 
  the 
  preceding 
  pages, 
  where 
  

   these 
  granulitic 
  veins 
  are 
  deflected 
  by 
  the 
  porphyritic 
  crystals 
  in 
  the 
  

   diorite, 
  and 
  both 
  facts, 
  taken 
  in 
  connexion 
  with 
  the 
  evidence 
  supplied 
  

   by 
  the 
  Kennack 
  foreshore, 
  show 
  that 
  the 
  porphyritic 
  diorite 
  was 
  

   injected 
  with 
  granite 
  after 
  its 
  intrusion 
  into 
  the 
  " 
  granulitic 
  " 
  group. 
  

  

  * 
  These 
  dykes 
  are 
  described 
  in 
  Messrs. 
  Fox 
  and 
  Somervail's 
  paper 
  referred 
  

   to 
  ante. 
  

  

  