Yol.  49.] 
CONGLOMERATES  IN  CAERNARVONSHIRE . 
453 
belong  to  the  upper  series — a  discovery  which  simplifies  matters 
greatly. 
Beginning  with  the  eastern  end  of  the  section  and  tracing  in¬ 
wards  the  conglomerate  m,  we  cannot  find  it  in  the  road  above 
owing  to  the  presence  of  a  mass  of  greenstone ;  but  in  the  grounds 
beyond,  opposite  Glyn  Padarn  at  2,  we  come  to  the  corresponding 
rocks  again.  .  Along  the  south-eastern  edge  of  these  grounds  we 
find  the  Purple  Slates  at  3,  which  are  worked  in  the  adjacent 
quarry  (4)  to  a  depth  of  quite  100  feet.  In  this  quarry  they  are 
seen  to  dip  at  angles  varying  from  45°  to  60°  to  the  south-east ; 
that  is  to  say,  they  are  rising  in  the  direction  of  2.  If  then  these 
Purple  Slates  were  continued  regularly,  we  ought  to  see  them  cropping 
out  all  over  these  grounds  ;  instead  of  which  we  find  within  a  "few 
yards  of  the  edge  a  number  of  crags  of  grit,  grey  slate,  and  conglo¬ 
merate  (see  fig.  8). 
Pig.  8. — Election  opposite  Glyn  Padarn. 
n.n.w.  s.s.e 
In  these,  if  we  pass  along  an  E.N.E.-W.S.W.  line,  that  is,  parallel 
to  the  strike  of  the  Purple  Slates ,  we  cross  a  definite  succession  of  dif¬ 
ferent  rocks,  with  a  gentle  dip  towards  the  E.H.E.  (see  fig.  9,  p.  454), 
so  that  the  lowest  bands,  which  are  grey  slates  of  the  ‘  Silurian  ’ 1 
type,  are  farthest  from  the  road ;  next  above  them  come  slightly- 
dipping  bands  of  very  coarse  conglomerate  with  many  slate-fragments, 
including  a  large  mass  of  purple  slate  lying  horizontally  on  the  top 
of  finer  conglomerate ;  and  nearer  the  road  again  are  crags,  which 
seen  on  their  strike-face  appear  horizontal,  composed  of  alternations 
of  hard  grey  slate  (transversely  cleaved)  and  coarse  grit.  This 
peculiar  alternation  of  thin  beds  of  slate  and  grit  is  unknown  to  me 
in  any  part  of  the  series  below  the  Bronllwyd  Grit,  in  which  it  has 
been  noted  twice,  viz.,  at  Bethesda  and  on  Elidr  Each ;  and  even  at 
Lianberis,  only  half-a-mile  from  here,  on  the  opposite  side  of  the 
Purple  Slates,  something  similar  is  seen  in  the  overlying  grits.  Thus 
1  By  this  term  I  mean  that  they  have  a  peculiar  ashen-grey  colour,  and 
in  weathering  show  brown  manganiferous  patches  on  them,  which,  so  far  as  my 
experience  goes,  is  very  characteristic  of  all  the  lower  beds  that  have  ever  been 
called  Silurian. 
