208 
MESSES.  H.  E OX  AND  J.  J.  H.  TEALL  ON  [May  1893, 
resembles  parts  of  the  Granulitic  Series.  Close  to  the  southern  end 
of  this  dyke  is  a  mass  of  the  typical  Granulitic  Series  (i),  with 
both  the  basic  and  the  acid  varieties  well  developed.  The  relation 
of  this  to  the  dyke  could  not,  however,  be  observed,  owing  to  fallen 
blocks.  Some  of  the  blocks  at  j  are  greenish-grey  serpentine,  con¬ 
taining  crystals  of  picotite  similar  to  those  seen  at  Lankidden  and 
elsewhere.  Another  basic  mass,  which  is  connected  with  a  dyke, 
may  be  seen  at  m  ;  although  it  is,  on  the  whole,  fairly  uniform  in 
composition,  thin  veins  of  an  acid  rock  may  be  observed  in  one  or 
two  places.  The  eastern  junction  with  the  serpentine  is  exposed 
for  about  6  feet ;  it  is  wavy  in  outline,  and  the  schistosity  in  the 
serpentine  is  cut  by  the  junction-surface,  as  is  also  the  foliation  in 
the  schist.1 
We  next  come  to  the  wedge-shaped  mass  of  granulitic  rock  G, 
which  forms  the  most  interesting  portion  of  the  section.  The 
thickness  of  the  wedge  at  the  base  is  about  20  feet,  but  this  rapidly 
diminishes  as  it  rises  in  the  cliff,  and  at  a  height  of  about  25  feet  is 
only  1  or  2  feet.  A  narrow  band  of  the  same  material  may  be 
traced  at  intervals  up  the  slope,  but  its  relations  to  the  surrounding 
rock  cannot  be  made  out  in  a  satisfactory  manner.  Tfye  wedge  is 
made  up  of  two  types  of  rock,  a  dioritic  type  and  a  granitic  type, 
the  former  of  which  occasionally  contains  small  porphyritic  felspars. 
The  relations  of  the  two  types  are  too  complicated  to  be  accurately 
represented  in  a  diagram.  The  granitic  type  occurs  in  puckered 
bands,  streaks,  and  lenticles.  Microscopic  examination  confirms 
the  view  that  we  have  in  this  wedge  a  genuine  representative  of 
the  Granulitic  Series,  which  was  formerly  supposed  to  occur  only  on 
the  east  coast  of  the  Lizard. 
We  have  now  to  describe  the  most  important  point  of  all  in 
connexion  with  this  wedge.  The  junction  with  the  serpentine  is 
well  exposed.  On  the  left  side  are  two  rounded  protuberances 
(B  &  (7,  fig.  4,  p.  209),  so  that  the  junction-line  presents  a  wavy 
appearance.  The  granulitic  mass  is  here  well  banded,  and  the 
banding  is  conformable  with  the  junction.  On  the  right-hand  side, 
at  D ,  there  is  a  tongue-like  process  of  rotten  serpentine,  and 
indications  of  the  same  feature  may  also  be  observed  on  the  left. 
Now  these  phenomena  seem  to  contradict  the  view  that  the  original 
rock  of  the  serpentine  was  intruded  into  a  solid  granulitic  complex. 
They  appear  to  indicate  that  the  granulitic  complex  was  either 
intruded  into  the  serpentine,  or  that  the  two  have  been  folded 
together  while  the  granulitic  complex  was  in  a  state  of  plasticity,  so 
that  bosses  and  tongues  of  serpentine  could  be  pushed  into  the 
yielding  mass  of  granulitic  material ;  or  finally,  and  this  we  regard 
as  the  least  probable,  that  the  serpentine  was  intruded  into  the 
granulitic  complex  while  this  was  in  a  plastic  state. 
1  The  letters  a,  k,  l,  p,  q  in  fig.  3  indicate  dykes  which  do  not  differ  in  any 
essential  particular  from  those  above  described.  The  mass  l  is  not  seen  when 
the  tide  is  so  high  as  shown  in  the  figure  :  it  lies  on  the  floor  of  the  foreshore, 
with  boulders  of  serpentine  on  the  top  of  it. 
