,206  COAST-SECTIONS  AT  THE  LIZARD.  [May  1 89 3. 
This  evidence  is  furnished  by  the  very  slide  we  are  describing. 
Ragged  cores  of  unaltered  augite  lie  in  some  of  the  hornblende- 
aggregates,  and  apparently  shade  off  into  them.  These  cores 
polarize  as  individuals ,  and  are  penetrated  by  lath-sliaped  sections  of 
felspar ,  ivhereas  the  hornblende  polarizes  as  aggregates  and  shows 
fluxion  round  the  felspars.  We  conclude,  therefore,  that  the 
original  rock  was  a  massive  ophitic  dolerite,  that  tho  parallel 
structure  is  the  result  of  fluxion  due  to  earth-stresses  after  the  con¬ 
solidation  of  the  last  mineral — that  is,  after  the  consolidation  of  the 
augite — and,  finally,  that  the  superinduced  plasticity  was  connected 
with  the  replacement  of  augite  by  hornblende. 
TV.  Relation  between  the  Serpentine  and  the  Grantjlitic 
Series  east  of  the  Lion  Rock. 
The  general  structure  of  the  coast  for  a  distance  of  about  120 
yards  (from  west  to  east)  is  indicated  in  fig.  3.  The  main  mass  ot 
the  cliff  is  formed  of  serpentine.  The  common  variety  weathers 
red,  and  contains  numerous  crystals  of  bastite.  It  is  therefore 
markedly  different  from  the  olivine-hornblende  serpentine  of  the  Ogo 
Lour  district. 
The  chine  c,  at  which  our  section  commences  on  the  west,  is 
evidently  determined  by  a  plane  of  disturbance,  and  the  brecciation 
which  may  be  observed  at  this  point  is  probably  connected  with 
the  disturbance.  It  is  only  seen  in  a  narrow  band,  measuring  a 
few  feet  across,  and  running  in  the  general  direction  of  the  chine. 
The  dyke  d  is  only  visible  for  a  few  yards,  and  does  not  maintain  a 
constant  thickness  for  any  considerable  portion  of  that  small  dis¬ 
tance.  It  is  formed  of  a  compact,  grey,  massive  rock,  too  much 
decomposed  for  precise  determination.  In  its  upper  part  it  has 
been  converted  into  a  series  of  lenticles  by  a  number  of  small 
oblique  faults.  The  gabbro-vein  e  can  be  traced  only  for  a  few 
yards  among  the  fallen  blocks.  It  must  have  been  of  the  extremely 
coarse  type  for  which  the  term  ‘  gabbro-pegmatite  ’  seems  appro¬ 
priate.  Pseudomorphs  after  diallage,  sometimes  measuring  1  inch 
or  more  across,  lie  in  a  matrix  of  pseudophite.  The  vein  is  about 
1  foot  thick,  and  it  may  be  seen  to  cut  across  the  foliation  of  the 
serpentine,  which  is  here  fairly  well  marked. 
The  dyke  /  occurs  at  a  place  where  there  has  been  much  disturb¬ 
ance.  The  lower  portion  (6  feet)  is  bordered  by  rotten  serpentine 
and  varies  in  thickness.  Where  the  dyke  is  narrow,  foliation  is 
strongly  marked.  Like  most  of  the  small  dykes  along  this  coast, 
it  is  so  altered  as  to  make  a  precise  petrographical  determination 
impossible.  The  freshest  portions  are,  however,  rich  in  biotite, 
and  it  is  probable  therefore  that  the  rock  most  nearly  resembles 
some  of  the  darker  members  of  the  (Iranulitic  Series.  The 
mass  h  is  fine-grained  and  well  foliated  in  places.  It  runs  parallel 
with  the  shore  for  about  18  or  20  feet,  and  then  turns  up  the 
cliff.  At  its  lowest  part  it  attains  a  thickness  of  about  3  feet,  but 
as  it  is  followed  up  the  cliff  it  is  seen  to  diminish  rapidly  in  thick¬ 
ness,  and  finally  to  disappear.  In  its  thicker  portions  it  closely 
