﻿THE 
  PEECAMBEIAN 
  (ARCHAEAN) 
  EOCKS 
  OF 
  SHEOPSHIEE. 
  119 
  

  

  12. 
  The 
  Peecahbeian 
  (Aech^an) 
  Rocks 
  of 
  Sheopshiee. 
  Part 
  II. 
  

   By 
  C. 
  Callaway, 
  Esq., 
  M.A., 
  D.Sc. 
  Lond., 
  F.G.S. 
  With 
  Notes 
  

   on 
  the 
  Miceoscopic 
  Stetjctuee 
  of 
  some 
  of 
  the 
  Rocks, 
  by 
  Prof. 
  

   T. 
  G. 
  Bonnet, 
  M.A., 
  F.R.S., 
  Sec.G.S. 
  (Read 
  December 
  21, 
  

   1881.) 
  

  

  In 
  1879*, 
  I 
  announced 
  to 
  the 
  Society 
  that 
  the 
  volcanic 
  rocks 
  of 
  the 
  

   Wrekin, 
  originally 
  supposed 
  to 
  be 
  "greenstone," 
  and 
  which 
  had 
  

   recently 
  been 
  described 
  by 
  Mr. 
  S. 
  Allportf 
  as 
  bedded 
  lavas 
  and 
  ashes, 
  

   were 
  Precambrian, 
  and 
  I 
  showed 
  that 
  rocks 
  of 
  the 
  same 
  age, 
  asso- 
  

   ciated 
  with 
  gneissic 
  strata 
  of 
  still 
  higher 
  antiquity, 
  formed 
  a 
  chain 
  

   of 
  hills 
  nearly 
  thirty 
  miles 
  in 
  length. 
  In 
  the 
  following 
  year, 
  in 
  a 
  

   paper 
  $ 
  " 
  On 
  a 
  second 
  Precambrian 
  group 
  in 
  the 
  Malvern 
  Hills," 
  I 
  

   sketched 
  the 
  history 
  of 
  the 
  physical 
  changes 
  which 
  the 
  Shropshire 
  

   range, 
  in 
  common 
  with 
  the 
  Malvern 
  chain, 
  had 
  undergone, 
  and 
  I 
  

   correlated 
  the 
  Salopian 
  gneissic 
  and 
  volcanic 
  series 
  respectively 
  with 
  

   the 
  metamorphic 
  axis 
  of 
  Malvern 
  and 
  the 
  felspathic 
  mass 
  east 
  of 
  

   the 
  Herefordshire 
  Beacon. 
  Further 
  attempts 
  at 
  correlation 
  have 
  

   not 
  led 
  to 
  decisive 
  results 
  ; 
  but 
  it 
  is 
  indubitable 
  that 
  there 
  are 
  strong 
  

   lithological 
  analogies 
  between 
  the 
  Wrekin 
  series 
  and 
  the 
  Archaean 
  

   rocks 
  south 
  of 
  Bangor, 
  as 
  well 
  as 
  between 
  the 
  Lilleshall 
  group 
  and 
  

   the 
  Charnwood 
  and 
  St.-David's 
  volcanic 
  series. 
  My 
  present 
  object 
  

   is 
  to 
  describe 
  a 
  second 
  area 
  of 
  Archaean 
  rocks 
  lying 
  further 
  to 
  the 
  

   west, 
  and 
  in 
  so 
  doing 
  to 
  present 
  additional 
  evidence 
  of 
  the 
  Precam- 
  

   brian 
  age 
  of 
  the 
  whole 
  group. 
  

  

  a. 
  General 
  Description 
  of 
  the 
  western 
  Archaean 
  Axis 
  of 
  Shropshire. 
  

  

  The 
  rocks 
  of 
  this 
  area 
  are 
  exposed 
  at 
  intervals 
  along 
  a 
  line 
  which 
  

   runs 
  roughly 
  parallel 
  to 
  the 
  Wrekin 
  and 
  Caer-Caradoc 
  chain, 
  at 
  a 
  

   distance 
  of 
  from 
  6 
  to 
  7 
  miles, 
  the 
  strip 
  of 
  country 
  which 
  lies 
  between 
  

   being 
  chiefly 
  occupied 
  by 
  the 
  Longmynd 
  group. 
  Looking 
  at 
  the 
  

   Survey 
  Map, 
  it 
  will 
  be 
  seen 
  that 
  down 
  the 
  valley 
  between 
  the 
  Long- 
  

   mynd 
  and 
  the 
  quartzite 
  ridge 
  of 
  the 
  Stiper 
  Stones 
  is 
  drawn 
  the 
  

   boundary 
  between 
  the 
  Longmynd 
  series 
  and 
  the 
  formation 
  which 
  

   Sir 
  R. 
  I. 
  Murchison 
  and 
  the 
  Survey 
  described 
  as 
  Lingula 
  Flags, 
  but 
  

   which 
  by 
  its 
  fossils 
  is 
  proved 
  to 
  be 
  the 
  equivalent 
  of 
  the 
  Shineton 
  

   Shales 
  (Tremadoc). 
  At 
  intervals 
  along 
  this 
  line 
  are 
  put 
  in 
  patches 
  

   of 
  " 
  greenstone," 
  most 
  of 
  which 
  prove 
  to 
  be 
  Archaean 
  rocks 
  of 
  varied 
  

   character 
  ; 
  but 
  occasionally 
  the 
  Archaeans 
  appear 
  at 
  spots 
  coloured 
  as 
  

   Cambrian 
  (Longmynd). 
  From 
  this 
  ancient 
  axis 
  the 
  Longmynd 
  

   rocks 
  and 
  the 
  Tremadoc 
  are 
  thrown 
  off 
  in 
  opposite 
  directions. 
  From 
  

   the 
  most 
  northerly 
  exposure 
  of 
  the 
  Archaean, 
  near 
  Pontesbury, 
  to 
  

   the 
  southern 
  end 
  of 
  the 
  chain, 
  near 
  Linley 
  Hall, 
  the 
  distance 
  is 
  

   about 
  11 
  miles. 
  Usually 
  the 
  old 
  rocks 
  form 
  low 
  hills 
  or 
  ridges 
  

  

  * 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxv. 
  p. 
  643. 
  

  

  t 
  Rid. 
  vol. 
  xxxiii. 
  p. 
  449. 
  \ 
  Ibid. 
  vol. 
  xxxvi. 
  p. 
  536. 
  

  

  Q.J.G.S. 
  No. 
  150. 
  x 
  

  

  