Yol.  49.] 
CONGLOMERATES  IX  CAERXARTOXSHIRE. 
445 
Commencing  from  the  felsite  (?/),  we 
have  first  a  narrow,  vertically-bounded 
band  of  coarse  conglomerate  («),  then  a 
greenstone  dyke  (a?),  then  some  halleflinta- 
like  material,  very  much  pulled  out  and 
becoming  purplish  at  the  top  (6),  then 
some  bluish-green  felspathic  grit,  dipping 
more  gently  up  the  lake  (c),  and  then  a 
large  mass  of  banded  green  slate  with  a 
lower  dip  in  the  same  direction  ( d ). 
After  some  interval  without  exposure  we 
come  to  some  more  banded  slate  dipping 
down  the  lake  at  about  45°  ( e ),  followed 
by  a  mass  of  greenstone  or  green  grit  (/) 
[not  properly  examined].  Then,  after  a 
hollow,  is  seen  a  cliff  of  remarkable  breccia 
commonly  called  a  conglomerate  ((/), 
which  is  vertically  bedded,  changing  in 
a  horizontal  direction  to  more  and  more 
felsitic  material  till  it  is  almost  a  felsite 
or  pure  felsitic  ash(7i).  Then,  after  some 
slight  obscurity,  comes  a  massive  con¬ 
glomerate  (i),  followed  by  a  hard,  blue 
banded  grit  with  an  easterly  dip  ( [Jc ),  and 
finally  comes  the  Red  Purple  Slate  (?). 
I  do  not  think  it  is  at  all  surprising  that 
this  section  should  have  been  interpreted 
as  showing  a  triple  repetition  of  the  same 
conglomerate  by  means  of  a  synclinal  and 
anticlinal.1  The  position  of  the  conglo¬ 
merate  (a)  in  a  horizontal  section  between 
the  felsite  and  the  slates  and  grits  ( b-cl ) 
is  naturally  explained  by  its  being  inter¬ 
mediate  in  age ;  yet,  owing  to  the  inter¬ 
vention  of  the  greenstone-dyke,  we  have 
no  definite  proof  of  this  :  it  is  quite  as 
likely  that  the  dyke  lies  along  a  fault. 
Then  there  is  undoubtedly  a  synclinal,  d 
corresponding  with  e,  possibly  also  c  with 
/,  and  it  may  well  be  suggested  that 
the  breccias  '  (g)  correspond  with  the 
finer  halleflintas  (6),  leading  to  h  corre¬ 
sponding  with  the  felsite  (y).  On  the 
other  side  of  7i,  however,  we  get  into 
difficulties  ;  the  conglomerate  i  resembles 
a ,  but  not  g,  and  there  is  nothing  but  the 
thin  mass  of  grit  Jc.  [the  section  is  drawn 
to  scale]  between  it  and  the  worked 
1  See  T.  G-.  Bonney,  Quart.  Journ.  Geol.  Soc. 
vol.  xxxy.  (1879)  p.  315. 
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