﻿28 
  T. 
  M'KENNY 
  HUGHES 
  ON 
  THE 
  GEOLOGY 
  OP 
  ANGLESEY. 
  

  

  Discussion. 
  

  

  Dr. 
  Roberts 
  drew 
  attention 
  to 
  the 
  fact 
  that 
  in 
  Anglesey 
  the 
  base- 
  

   ment 
  conglomerate 
  was 
  composed 
  of 
  quartz 
  pebbles, 
  while 
  in 
  the 
  

   Bangor 
  district 
  it 
  consisted 
  of 
  felsite 
  pebbles. 
  The 
  Twt-Hill 
  conglo- 
  

   merate 
  at 
  Caernarvon 
  exactly 
  resembles 
  that 
  in 
  Anglesey, 
  and, 
  like 
  

   it, 
  rests 
  on 
  the 
  granitoid 
  axis. 
  If 
  the 
  Anglesey 
  conglomerate 
  was 
  

   the 
  Cambrian 
  conglomerate, 
  it 
  was 
  extremely 
  probable 
  that 
  the 
  Twt- 
  

   Hill 
  conglomerate 
  was 
  of 
  the 
  same 
  age. 
  

  

  Dr. 
  Hicks 
  agreed 
  with 
  Prof. 
  Hughes 
  in 
  regarding 
  the 
  rocks 
  re- 
  

   ferred 
  to 
  in 
  Anglesey 
  as 
  forming 
  the 
  base 
  of 
  the 
  Cambrian, 
  and 
  as 
  

   being 
  entirely 
  distinct 
  from 
  the 
  Pre-Cambrian. 
  The 
  pebbles 
  and 
  

   matrix 
  of 
  the 
  conglomerates 
  varied 
  with 
  the 
  rocks 
  upon 
  which 
  they 
  

   reposed, 
  and 
  from 
  which 
  the} 
  7 
  must 
  have 
  been 
  chiefly 
  derived. 
  The 
  

   mistake 
  made 
  in 
  associating 
  them 
  with 
  the 
  Pre-Cambrian 
  was 
  due 
  

   to 
  a 
  want 
  of 
  the 
  recognition 
  of 
  this 
  fact. 
  He 
  had 
  examined 
  these 
  

   sections 
  and 
  also 
  the 
  one 
  at 
  Twt 
  Hill 
  recently, 
  and 
  he 
  believed 
  that 
  

   the 
  interpretations 
  given 
  by 
  Prof. 
  Hughes 
  and 
  Dr. 
  Roberts 
  were 
  

   correct. 
  

  

  