﻿KOCKS 
  OF 
  THE 
  LEICESTERSHIRE 
  COAL-FIELD. 
  37 
  

  

  proof 
  that 
  denudation 
  had 
  bared 
  some 
  of 
  the 
  older 
  rocks 
  of 
  their 
  

   overlying 
  Coal-measures, 
  and 
  it 
  is 
  the 
  re-arranged 
  talus 
  and 
  " 
  screes 
  " 
  

   from 
  the 
  harder 
  portions 
  of 
  these 
  older 
  rocks 
  which 
  now 
  form 
  the 
  

   brecciated 
  bands 
  in 
  the 
  Leicestershire 
  Permians 
  *. 
  

  

  (6) 
  APPENDIX. 
  

   The 
  Igneous 
  Pocks 
  or 
  the 
  Market 
  Bosworth 
  Borings. 
  

  

  The 
  igneous 
  rocks 
  which 
  have 
  been 
  penetrated 
  in 
  the 
  deep 
  borings 
  

   of 
  Bosworth 
  Wharf 
  and 
  the 
  Cowpasiure, 
  near 
  Market 
  Bosworth, 
  

   have 
  not 
  hitherto 
  been 
  described. 
  They 
  occur, 
  as 
  we 
  have 
  already 
  

   seen, 
  at 
  the 
  northern 
  end 
  of 
  the 
  Sub-Triassic 
  ridge, 
  which 
  extends 
  

   from 
  Sapcote 
  to 
  Market 
  Bosworth, 
  and 
  they 
  appear 
  to 
  be 
  intrusive 
  

   in 
  bluisb-black 
  shales, 
  which, 
  we 
  have 
  every 
  reason 
  to 
  believe, 
  are 
  

   identical 
  with 
  the 
  Stockingford 
  iShales 
  of 
  the 
  Nuneaton 
  district. 
  

   The 
  fact 
  tiiat 
  fragments 
  of 
  these 
  igneous 
  rocks, 
  doubtless 
  derived 
  

   from 
  this 
  immediate 
  neighbourhood, 
  occur 
  in 
  the 
  Permian 
  breccia 
  a 
  

   few 
  miles 
  further 
  north, 
  is 
  sufficient 
  excuse 
  for 
  my 
  dwelling 
  some- 
  

   what 
  in 
  detail 
  upon 
  the 
  results 
  of 
  their 
  examination. 
  

  

  I 
  must 
  once 
  more 
  express 
  my 
  thanks 
  to 
  Professor 
  Bonney 
  for 
  his 
  

   careful 
  examination 
  of 
  the 
  slices 
  of 
  these 
  rocks, 
  and 
  to 
  Mr. 
  T. 
  H. 
  

   Waller 
  for 
  a 
  determination 
  of 
  their 
  relation 
  to 
  the 
  Warwickshire 
  

   diorites, 
  with 
  which 
  he 
  is 
  so 
  well 
  acquainted. 
  

  

  1. 
  From 
  the 
  Cowpasture 
  Boring. 
  Depth 
  509 
  feet. 
  — 
  This 
  is 
  a 
  

   moderately 
  fine-grained 
  rock, 
  which 
  was 
  probably 
  once 
  an 
  ophitic 
  

   dolerite. 
  The 
  felspar 
  is 
  plagioclase, 
  but 
  much 
  altered, 
  and 
  the 
  py- 
  

   roxenic 
  mineral 
  has 
  been 
  replaced 
  by 
  pale 
  viridite, 
  with 
  a 
  few 
  specks 
  

   of 
  opacite. 
  There 
  are 
  some 
  crystals 
  and 
  grains 
  of 
  iron-oxide, 
  which 
  

   are 
  doubtless 
  in 
  part 
  haematite, 
  and 
  some 
  pyrite. 
  There 
  is 
  a 
  little 
  

   free 
  quartz, 
  which, 
  from 
  its 
  frequent 
  association 
  with 
  calcite 
  or 
  

   dolomite, 
  may 
  be 
  looked 
  upon 
  as 
  probably 
  of 
  secondary 
  origin. 
  

  

  2. 
  Bosworth 
  Wharf 
  Boring. 
  Depth 
  1275 
  feet. 
  — 
  The 
  minerals 
  

   of 
  this 
  specimen 
  are 
  much 
  decomposed. 
  It 
  is 
  a 
  holocrystalline 
  

   mixture, 
  chiefly 
  of 
  felspar 
  and 
  pyroxene 
  mineral, 
  the 
  former 
  being 
  

   of 
  a 
  grey 
  brownish 
  colour 
  in 
  transmitted 
  light, 
  but 
  with 
  crossed 
  

   Nicols 
  giving 
  very 
  pale 
  whitish-grey 
  tints, 
  and 
  still 
  distinctly 
  indi- 
  

   cating 
  the 
  twinning 
  of 
  plagioclase, 
  probably 
  labradorite. 
  

  

  The 
  pyroxene 
  mineral 
  is 
  replaced 
  by 
  a 
  very 
  pale-green 
  mineral, 
  

   which, 
  with 
  crossed 
  Nicols, 
  shows 
  an 
  aggregate 
  structure 
  acting 
  very 
  

   feebly 
  on 
  polarized 
  light, 
  and 
  a 
  brown 
  or 
  black 
  ferruginous 
  mineral. 
  

   The 
  latter 
  is 
  often 
  arranged 
  in 
  parallel 
  flakes, 
  indicating 
  that 
  its 
  

   deposition 
  has 
  been 
  determined 
  by 
  pre-existing 
  cleavage-planes. 
  The 
  

   pyroxene 
  constituent 
  has 
  consolidated 
  later 
  than 
  the 
  felspar, 
  so 
  that 
  

   the 
  rock 
  has 
  an 
  ophitic 
  structure. 
  

  

  There 
  are 
  some 
  hexagonal 
  prisms 
  of 
  apatite 
  and 
  a 
  little 
  dolo- 
  

   mite 
  (?). 
  

  

  3. 
  Bosworth 
  Wharf 
  Boring. 
  Depth 
  1265 
  feet. 
  — 
  This 
  is 
  an 
  ophitic 
  

  

  * 
  An 
  excellent 
  example 
  of 
  such 
  a 
  rearranged 
  talus 
  from 
  the 
  Cbarnwood 
  

   rocks 
  may 
  be 
  seen 
  in 
  the 
  thick 
  lveuper 
  breccia 
  on 
  the 
  flanks 
  of 
  Cbarnwood 
  

   Forest 
  at 
  Tbringstone. 
  

  

  