CONGLOMERATES  IN  CAERNARVONSHIRE, 
447 
Vol.  49.] 
pfCr>m§Pf 
>  v  ,YTy'<7  t'jM 
jl  v -Jforomvy 
J'fuJtMr.rLf'  i°l 
3^r?'AT  Av 
LVYf 
r,  : 
K.  'V-  >' A  \  ° 
Av  V  / 
AdJr*s 
1  xz-rA'is 
Prof.  Bonney,  for  at  10  the  conglomerate  shades  so  gradually  into 
the  reconstructed  felsite  that  only  an  occasional  quartz-pebble  in¬ 
dicates  the  nature  of  the  rock,  and  it  is  impossible  to  draw  the  line 
(though  we  know  it  must  exist)  in  the  field.  This  difficulty  dis¬ 
appears  if  the  conglomerate  is  younger  than  all. 
Next,  on  the 
western  side,  the  Fig.  2. — Map  of  Country  from  Llyn  Padarn 
conglomerate  ( a )  to  Y  Bigh 
may  be  traced  up 
in  great  crags  from 
8  by  10,  25,  as  far 
as  11  ;  but  there 
it  suddenly  stops, 
and  Pale  Slate  is 
found  at  12,  at  a 
lower  level  and 
close  against  the 
felsite,  13.  It  is 
true  that  this  slate 
contains  pebbles  at 
14,  15, 16,  but  the 
whole  rock  is  very 
different  from  the 
crag  of  conglome¬ 
rate  which  comes 
on  again  at  17. 
These  observations 
are  well  enough 
explained  if  the 
conglomerate  over- 
lies,  and  is  let 
down  in  a  fold  or 
by  a  fault  at  8 ; 
but  to  account  for 
them,  if  it  lies 
below  throughout, 
would  require  a 
very  rapid  and  dis¬ 
continuous  change 
in  its  character. 
On  the  other  side 
of  the  area  the 
observations  seem 
more  decisive. 
The  nnconform- 
able  conglomerate 
(A)  at  2  can  be 
traced  up  thence 
Yify JASA-'t  jP  A-aTa 
Jfjt  A  7x  Add-/  At  a 
>a\ 
VO 
LLYN  PADARN 
Scale  :  4 inches  =  / mil e  . 
A'd-d  Belsilie  Mocks 
Bc/Jaled,  Slates 
Purple,  Slate, 
Various  Or  its  t 
ConprlvmcT-aCes  4:  Preocias 
Greenstone,  JJvkes 
. Vosb-LlcatJjf,)‘?s ” 
Conglomerate s  &  Grits 
again 
along 
by  18,  19  to  3  and  20,  and 
from  21  to  22,  and  is  seen  also  at  23.  This,  according  to  the 
old  interpretation,  forms  the  eastern  part  of  a  synclinal,  of 
