﻿122 
  C. 
  CALLAWAY 
  ON 
  THE 
  PKECAMBKIAN 
  (AECHJEAN) 
  

  

  There 
  is 
  no 
  intrusive 
  rock 
  near 
  ; 
  but 
  pebbles 
  of 
  rhyolite 
  (no. 
  58, 
  

   p. 
  124) 
  are 
  contained 
  in 
  the 
  shale. 
  Some 
  of 
  the 
  rhyolite 
  is 
  banded 
  ; 
  

   and 
  these 
  enclosures 
  are, 
  I 
  believe, 
  derived 
  from 
  the 
  Archaean. 
  

  

  In 
  a 
  field 
  to 
  the 
  north-east 
  of 
  the 
  Caradoc 
  shale 
  is 
  a 
  small 
  ex- 
  

   posure 
  of 
  micaceo-arenaceous 
  flags 
  of 
  a 
  dark 
  grey 
  colour, 
  dipping 
  south 
  

   by 
  a 
  little 
  east, 
  and 
  probably 
  belonging 
  to 
  the 
  Arenig 
  series. 
  

  

  I 
  have 
  called 
  attention 
  to 
  these 
  detached 
  fragments, 
  occurring 
  on 
  

   the 
  strike 
  of 
  the 
  Tremadoc 
  shales, 
  as 
  indicating 
  the 
  powerful 
  dis- 
  

   locations 
  which 
  have 
  ruptured 
  the 
  rocks 
  along 
  this 
  Archaean 
  axis. 
  

  

  2. 
  Gatten 
  Lodge. 
  — 
  Following 
  the 
  axis 
  in 
  a 
  southerly 
  direction, 
  we 
  

   come, 
  in 
  about 
  three 
  miles, 
  to 
  a 
  small 
  elevation 
  near 
  Gatten 
  Lodge. 
  

   Rock 
  is 
  exposed 
  in 
  a 
  quarry 
  near 
  the 
  road, 
  with 
  an 
  apparent 
  dip 
  

   to 
  the 
  north-east. 
  The 
  prevailing 
  type 
  (no. 
  59, 
  p. 
  125) 
  is 
  purplish 
  

   and 
  compact, 
  resembling 
  the 
  flinty 
  hornstone-like 
  rock 
  so 
  common 
  

   in 
  the 
  Pebidian. 
  In 
  places 
  it 
  is 
  brecciated, 
  the 
  fragments, 
  some 
  of 
  

   which 
  are 
  subangular, 
  being 
  of 
  quartz 
  and 
  the 
  purple 
  hornstone. 
  

  

  3. 
  Knolls 
  Midge. 
  — 
  The 
  next 
  Archaean 
  mass 
  occupies 
  part 
  of 
  a 
  

   ridge 
  which 
  I 
  have 
  named 
  from 
  a 
  house 
  at 
  its, 
  north 
  end, 
  lying 
  a 
  

   mile 
  and 
  a 
  half 
  south-south-west 
  of 
  Gatten 
  Lodge. 
  It 
  is 
  about 
  one 
  

   mile 
  long, 
  striking 
  with 
  the 
  axis. 
  The 
  rocks 
  of 
  which 
  it 
  is 
  composed 
  are 
  

   varied 
  and 
  generally 
  difficult 
  of 
  determination. 
  Some 
  are 
  intrusive. 
  

   At 
  the 
  north 
  end 
  is 
  a 
  greenstone 
  allied 
  to 
  diorite 
  (no. 
  60, 
  p. 
  125). 
  

   Felsitic 
  rocks 
  occur 
  further 
  along 
  the 
  ridge. 
  At 
  the 
  south 
  end 
  is 
  a 
  

   purplish 
  hornstone, 
  similar 
  to 
  the 
  Gatten-Lodge 
  type. 
  

  

  4. 
  Cold 
  Hill. 
  — 
  West-north-west 
  of 
  the 
  farm 
  of 
  Cold 
  Hill, 
  on 
  the 
  

   line 
  of 
  fault 
  continuous 
  with 
  Knolls 
  Ridge, 
  there 
  is 
  a 
  slight 
  exposure 
  

   of 
  purple 
  hornstone 
  and 
  breccia. 
  

  

  5. 
  Chittol. 
  — 
  In 
  this 
  hill, 
  about 
  a 
  mile 
  from 
  the 
  last 
  locality, 
  is 
  

   found 
  a 
  greenish 
  compact 
  rock, 
  which 
  I 
  believe 
  to 
  be 
  sedimentary. 
  

   It 
  has 
  the 
  splintery 
  fracture 
  characteristic 
  of 
  the 
  hornstone-like 
  rocks 
  

   of 
  the 
  Pebidian, 
  to 
  which 
  it 
  is 
  probably 
  to 
  be 
  referred. 
  

  

  6. 
  Knolls 
  Wood. 
  — 
  This 
  locality 
  is 
  a 
  mile 
  further 
  to 
  the 
  south- 
  

   south-west. 
  The 
  rock 
  is 
  hard 
  and 
  compact, 
  and 
  on 
  fractured 
  sur- 
  

   faces 
  looks 
  like 
  a 
  quartz-felsite 
  ; 
  but 
  where 
  weathered 
  it 
  is 
  seen 
  to 
  

   be 
  clastic, 
  bits 
  of 
  quartz 
  and 
  of 
  a 
  reddish 
  granitoid 
  rock 
  being 
  clearly 
  

   visible. 
  The 
  latter 
  variety 
  is 
  not 
  unlike 
  the 
  (presumed) 
  Dimetian 
  of 
  

   the 
  eastern 
  axis. 
  Some 
  of 
  the 
  fragments 
  display 
  a 
  foliated 
  struc- 
  

   ture. 
  Altered 
  grits 
  similar 
  to 
  this 
  rock 
  occur 
  in 
  the 
  Caer-Caradoc 
  

   chain 
  ; 
  and 
  as 
  the 
  strikes 
  in 
  both 
  localities 
  are 
  the 
  same 
  (east 
  and 
  

   west), 
  and 
  if 
  produced 
  would 
  coincide, 
  it 
  is 
  probable 
  that 
  the 
  rocks 
  

   of 
  Knolls 
  Wood 
  occupy 
  about 
  the 
  same 
  horizon 
  as 
  those 
  of 
  Caer 
  

   Caradoc. 
  

  

  7. 
  Ridge 
  west 
  of 
  Linley 
  Hall. 
  — 
  This 
  elevation, 
  one 
  mile 
  from 
  the 
  

   last 
  locality, 
  forms 
  the 
  termination 
  to 
  the 
  south 
  of 
  the 
  western 
  

   Archaean 
  chain 
  of 
  ridges. 
  It 
  is 
  composed 
  mainly 
  of 
  hornstone 
  or 
  

   halleflinta 
  (no. 
  61, 
  p. 
  125), 
  purple 
  and 
  green, 
  which 
  does 
  not 
  quite 
  so 
  

   closely 
  resemble 
  the 
  hornstone 
  previously 
  described 
  as 
  it 
  resembles 
  

   certain 
  varieties 
  in 
  the 
  Wrekin, 
  Lilleshall 
  Hill, 
  and 
  the 
  Malverns. 
  

   The 
  Archaean 
  is 
  broken 
  through 
  by 
  dolerite. 
  

  

  The 
  purple 
  conglomerate 
  east 
  of 
  Pontesford 
  Hill, 
  in 
  its 
  course 
  

  

  