﻿126 
  THE 
  PEECAMBELAN 
  (AECH-EAN) 
  EOCKS 
  OF 
  SHEOPSHIEE, 
  

  

  Discussion. 
  

  

  The 
  Peesident 
  said 
  that 
  Dr. 
  Callaway's 
  views 
  would 
  much 
  alter 
  

   the 
  stratigraphy 
  of 
  the 
  deep 
  valley 
  between 
  the 
  Longmynd 
  and 
  Stiper 
  

   Stones. 
  He 
  had 
  no 
  doubt 
  Tremadoc 
  rocks 
  were 
  in 
  that 
  valley; 
  

   whether 
  the 
  Stiper 
  Stones 
  were 
  Upper 
  Tremadoc 
  or 
  Arenig, 
  and 
  

   whether 
  contemporaneous 
  with 
  the 
  white 
  grit 
  of 
  North 
  Wales, 
  was 
  

   a 
  dubious 
  question 
  ; 
  he 
  invited 
  discussion. 
  

  

  Dr. 
  Hicks 
  said 
  he 
  had 
  but 
  slightly 
  examined 
  the 
  district. 
  The 
  

   paper 
  was 
  an 
  important 
  one. 
  There 
  appeared 
  to 
  be 
  evidence 
  of 
  

   Precambrian 
  rocks 
  in 
  contact 
  with 
  admitted 
  Cambrian 
  rocks; 
  so 
  

   that 
  in 
  this 
  region 
  also, 
  as 
  in 
  the 
  Welsh 
  areas, 
  we 
  had 
  a 
  base-line. 
  

   The 
  paper 
  was 
  important 
  also 
  as 
  showing 
  that 
  certain 
  types 
  of 
  rocks 
  

   were 
  characteristic 
  of 
  the 
  Precambrian 
  groups 
  over 
  wide 
  areas. 
  

   Some 
  years 
  since 
  he 
  had 
  expressed 
  the 
  view 
  that 
  the 
  Stiper 
  Stones 
  

   were 
  of 
  Arenig 
  age 
  and 
  about 
  the 
  horizon 
  of 
  the 
  Grit-band 
  of 
  

   Caernarvonshire 
  mentioned 
  by 
  the 
  President. 
  

  

  Mr. 
  Etjtlet 
  said 
  it 
  struck 
  him 
  as 
  possible 
  that 
  these 
  rhyolite 
  

   rocks 
  occurred 
  on 
  the 
  horizon 
  of 
  the 
  Bala 
  limestone. 
  Also 
  Mr. 
  

   Allport 
  had 
  suggested 
  that 
  perlitic 
  rocks, 
  associated 
  with 
  beds 
  

   mapped 
  by 
  the 
  Geological 
  Survey 
  as 
  Caradoc, 
  were 
  Precambrian. 
  

   He 
  thought 
  it 
  worth 
  reconsidering 
  whether 
  these 
  might 
  not 
  be 
  

   really 
  of 
  Bala 
  or 
  Llandeilo 
  age. 
  The 
  fragments 
  might 
  constitute 
  

   old 
  volcanic 
  breccias 
  or 
  tuffs. 
  

  

  Prof. 
  Bonnet 
  said 
  that 
  the 
  rocks 
  of 
  the 
  Wrekin 
  were 
  certainly 
  

   agglomerates, 
  and 
  that 
  fragments 
  of 
  the 
  rhyolite 
  certainly 
  occurred 
  

   in 
  the 
  so-called 
  Wrekin 
  quartzites, 
  which 
  he 
  believed 
  were 
  now 
  ad- 
  

   mitted 
  to 
  underlie 
  Tremadoc 
  rocks. 
  Hence 
  they 
  could 
  not 
  be 
  of 
  

   Bala 
  age. 
  

  

  Dr. 
  Callaway 
  said 
  that 
  he 
  proposed 
  on 
  a 
  future 
  occasion 
  to 
  give 
  

   more 
  detailed 
  sections 
  of 
  the 
  country. 
  As 
  for 
  Mr. 
  Bntley's 
  sug- 
  

   gestion 
  ; 
  — 
  over 
  the 
  quartzite, 
  which 
  contained 
  rhyolite 
  fragments, 
  

   was 
  Hollybush 
  sandstone, 
  and 
  over 
  that, 
  Tremadoc 
  ; 
  further, 
  

   rhyolitic 
  fragments 
  occurred 
  in 
  the 
  conglomerate 
  of 
  the 
  Longmynd, 
  

   and 
  even 
  in 
  the 
  finer 
  beds 
  ; 
  so 
  he 
  thought 
  the 
  Archaean 
  age 
  of 
  the 
  

   rhyolites 
  was 
  proved 
  beyond 
  all 
  question. 
  

  

  