﻿XC 
  PE0CEED1NGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [May 
  1897, 
  

  

  older 
  than 
  the 
  Schistes 
  de 
  St. 
  L6. 
  In 
  Aldemey 
  granitic 
  rocks 
  

   underlie 
  Gres 
  Eelspathique. 
  The 
  crystallines 
  of 
  Guernsey 
  and 
  of 
  

   Sark 
  cannot 
  be 
  dated, 
  but 
  it 
  is 
  reasonable 
  to 
  suppose 
  that 
  they 
  

   are 
  of 
  about 
  the 
  same 
  age 
  as 
  those 
  in 
  the 
  other 
  islands, 
  while 
  the 
  

   hornblende-schists 
  of 
  Sark 
  are 
  precisely 
  the 
  same 
  as 
  those 
  of 
  the 
  

   Lizard, 
  and 
  there 
  are 
  moreover 
  old-looking 
  gneisses. 
  The 
  occurrence 
  

   of 
  undoubted 
  Cambrian 
  rocks 
  in 
  the 
  areas 
  last 
  referred 
  to, 
  and 
  

   unconformable 
  to 
  the 
  volcanic 
  and 
  gneiss-rocks, 
  shows 
  clearly 
  that 
  

   the 
  physical 
  changes 
  which 
  affected 
  the 
  British 
  Isles 
  also 
  extended 
  

   over 
  wide 
  areas 
  in 
  Western 
  Europe. 
  

  

  These 
  discoveries, 
  moreover, 
  add 
  confirmatory 
  evidence 
  in 
  support 
  

   of 
  the 
  contention 
  in 
  my 
  paper 
  read 
  before 
  the 
  Society 
  in 
  ]875, 
  

   p. 
  558, 
  where 
  I 
  maintain 
  that, 
  wherever 
  in 
  the 
  European 
  areas 
  

   the 
  rocks 
  l 
  belonging 
  to 
  the 
  old 
  pre-Cambrian 
  continent 
  are 
  now 
  

   found 
  exposed, 
  they 
  show 
  every 
  indication 
  of 
  having 
  been 
  old 
  

   land-surfaces 
  before 
  the 
  overlying 
  rocks 
  had 
  been 
  deposited, 
  and 
  

   almost 
  invariably 
  the 
  lowest 
  beds 
  in 
  contact 
  with 
  them 
  are 
  either 
  

   sandstones 
  or 
  conglomerates, 
  whether 
  they 
  belong 
  to 
  the 
  Cam- 
  

   brian 
  or 
  the 
  Silurian.' 
  (Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxi.) 
  

  

  Ireland. 
  

  

  Though 
  it 
  is 
  now 
  fully 
  admitted 
  that 
  pre-Cambrian 
  rocks 
  

   occur 
  in 
  several 
  areas 
  in 
  Ireland, 
  some 
  doubt 
  still 
  exists 
  as 
  to 
  the 
  

   exact 
  position 
  of 
  the 
  rocks 
  whieh 
  have 
  been 
  classed 
  as 
  Cambrian 
  in 
  

   that 
  island. 
  They 
  are 
  known 
  to 
  occur 
  only 
  at 
  Howth, 
  about 
  Bray, 
  

   and 
  in 
  Wexford. 
  

  

  Mr. 
  A. 
  M 
  c 
  Henry 
  and 
  Mr. 
  W. 
  W. 
  Watts, 
  in 
  their 
  ' 
  Guide 
  to 
  the 
  

   Collections 
  of 
  Hocks 
  and 
  Possils 
  belonging 
  to 
  the 
  Geological 
  Survey 
  

   of 
  Ireland 
  ' 
  (1895), 
  say 
  that 
  the 
  only 
  fossils 
  hitherto 
  obtained 
  from 
  

   these 
  rocks 
  are 
  OldJmmia, 
  which 
  is 
  of 
  ' 
  doubtful 
  but 
  probably 
  of 
  

   organic 
  origin/ 
  and 
  tracks 
  and 
  burrows 
  of 
  worms, 
  and 
  the 
  micro- 
  

   scopic 
  bodies 
  from 
  the 
  slates 
  of 
  Howth, 
  stated 
  by 
  Prof. 
  Sollas 
  ' 
  to 
  

   have 
  the 
  appearance 
  of 
  being 
  relics 
  of 
  minute 
  animals 
  (radiolaria).' 
  

  

  Prof. 
  Sollas 
  has 
  also 
  more 
  recently 
  described 
  an 
  obscure 
  ' 
  but 
  

   probably 
  organic 
  structure 
  under 
  the 
  name 
  Pucksia 
  M 
  c 
  Henryi 
  ' 
  

   from 
  these 
  rocks. 
  The 
  strata 
  are 
  pierced 
  by 
  dykes 
  of 
  igneous 
  rocks, 
  

   but 
  ' 
  no 
  contemporaneous 
  volcanic 
  rocks 
  are 
  known 
  ' 
  in 
  them. 
  

  

  As 
  it 
  would 
  occupy 
  far 
  more 
  space 
  than 
  it 
  would 
  be 
  reasonable 
  

   to 
  ask 
  you 
  to 
  grant 
  me 
  for 
  this 
  address, 
  if 
  I 
  were 
  to 
  attempt 
  

   to 
  review 
  all 
  the 
  work 
  which 
  has 
  been 
  done 
  among 
  tbese 
  rocks 
  

   during 
  the 
  past 
  30 
  or 
  35 
  years, 
  1 
  have 
  thought 
  it 
  advisable 
  to 
  

  

  