﻿ROCKS 
  OF 
  THE 
  LEICESTERSHIRE 
  COAL-EIELD. 
  6 
  

  

  cestershire 
  Coal-field 
  rest 
  iviih 
  the 
  most 
  striking 
  unconformity 
  upon 
  

   the 
  true 
  Coal-measures. 
  In 
  proof 
  of 
  this, 
  I 
  will 
  mention 
  the 
  following 
  

   facts 
  : 
  — 
  At 
  Brizlincote 
  the 
  breccias 
  rest 
  upon 
  the 
  " 
  Well 
  " 
  coal, 
  

   whilst, 
  when 
  followed 
  along 
  their 
  line 
  of 
  strike 
  for 
  a 
  distance 
  of 
  only 
  

   2000 
  yards 
  further 
  south, 
  they 
  are 
  found, 
  at 
  the 
  Newhall 
  Park 
  Col- 
  

   liery, 
  in 
  contact 
  with 
  the 
  Nether 
  Main 
  Coal, 
  having 
  consequently 
  

   overlapped 
  the 
  Coal-measures 
  in 
  this 
  short 
  distance 
  through 
  a 
  ver- 
  

   tical 
  thickness 
  of 
  450 
  feet. 
  Again, 
  only 
  2 
  J 
  miles 
  east 
  of 
  Newhall 
  

   Park, 
  at 
  Swadlincote, 
  the 
  breccias 
  immediately 
  overlie 
  almost 
  the 
  

   highest 
  known 
  coals 
  of 
  the 
  district, 
  occurring 
  at 
  a 
  horizon 
  861 
  feet 
  

   above 
  the 
  Main 
  Coal. 
  So 
  that 
  within 
  a 
  very 
  small 
  area 
  the 
  brecciated 
  

   series 
  occurs 
  in 
  contact 
  with 
  Coal-measures 
  separated 
  from 
  each 
  other 
  

   by 
  a 
  vertical 
  distance 
  of 
  over 
  1300 
  feet, 
  almost 
  the 
  entire 
  thickness 
  

   of 
  the 
  productive 
  portion 
  of 
  the 
  Coal-field. 
  If 
  any 
  further 
  proof 
  of 
  

   unconformity 
  were 
  necessary, 
  it 
  is 
  afforded 
  by 
  the 
  detailed 
  sections 
  

   to 
  be 
  referred 
  to 
  later 
  on, 
  and 
  by 
  the 
  fact 
  that 
  the 
  great 
  Boothorpe 
  

   fault, 
  which 
  traverses 
  the 
  Coal-field 
  in 
  a 
  N.N.W. 
  and 
  S.S.E. 
  direc- 
  

   tion, 
  whilst 
  dislocating 
  the 
  Coal-measures 
  near 
  "Woodville 
  to 
  the 
  

   extent 
  of 
  at 
  least 
  1000 
  feet, 
  affects 
  the 
  overlying 
  brecciated 
  series 
  at 
  

   the 
  most 
  20 
  or 
  30 
  feet. 
  There 
  cannot, 
  therefore, 
  be 
  the 
  slightest 
  

   doubt 
  that 
  the 
  view 
  expressed 
  by 
  Professor 
  Hull 
  (Survey 
  Memoir, 
  

   p. 
  57) 
  that 
  these 
  strata 
  " 
  do 
  not 
  form 
  part 
  of 
  the 
  coal-formation, 
  but 
  

   are 
  of 
  more 
  recent 
  origin," 
  is 
  the 
  correct 
  one. 
  

  

  On 
  the 
  other 
  hand 
  their 
  relation 
  to 
  the 
  overlying 
  Bunter 
  Con- 
  

   glomerates 
  is 
  not 
  at 
  first 
  sight 
  quite 
  clear. 
  

  

  It 
  has 
  been 
  noted 
  that 
  the 
  Bunter 
  Conglomerates 
  do 
  not 
  occur 
  east 
  

   of 
  a 
  line 
  drawn 
  from 
  Measham 
  to 
  Ingleby 
  ; 
  the 
  brecciated 
  series, 
  

   however, 
  does 
  occur 
  in 
  one 
  or 
  two 
  spots 
  east 
  of 
  this 
  line, 
  and 
  in 
  these 
  

   cases 
  is 
  succeeded 
  upwards 
  by 
  the 
  Lower 
  Xeuper 
  Sandstone. 
  Prom 
  

   the 
  fact 
  of 
  this 
  eastward 
  overlap 
  by 
  higher 
  beds 
  of 
  the 
  Trias, 
  Prof. 
  

   Hull 
  concludes 
  (Survey 
  Memoir, 
  p. 
  58) 
  that 
  the 
  breccias 
  do 
  not 
  belong 
  

   to 
  this 
  latter 
  formation, 
  and 
  doubtfully 
  refers 
  them 
  to 
  the 
  Permian. 
  

  

  This 
  evidence 
  is, 
  however, 
  no 
  absolute 
  proof 
  in 
  itself 
  of 
  the 
  ex- 
  

   istence 
  of 
  a 
  stratigraphical 
  break, 
  amounting 
  to 
  an 
  unconformity, 
  

   between 
  the 
  brecciated 
  series 
  and 
  the 
  Trias 
  ; 
  for 
  we 
  must 
  bear 
  in 
  

   mind 
  that 
  we 
  are 
  in 
  close 
  proximity 
  to 
  an 
  old 
  shore-line, 
  which 
  we 
  

   know 
  gradually 
  receded 
  eastward 
  during 
  subsidence 
  of 
  the 
  old 
  

   Carboniferous 
  land 
  : 
  hence 
  it 
  seemed 
  to 
  me 
  by 
  no 
  means 
  improbable 
  

   that 
  the 
  breccias 
  might, 
  after 
  all, 
  belong 
  to 
  the 
  base 
  of 
  the 
  Trias, 
  and 
  

   represent 
  marginal 
  deposits 
  which 
  swept 
  up 
  the 
  sides 
  of 
  the 
  gradually 
  

   submerged 
  land, 
  bearing 
  the 
  same 
  relation 
  to 
  the 
  several 
  divisions 
  

   of 
  the 
  Trias 
  in 
  this 
  part 
  of 
  the 
  country 
  as 
  the 
  Dolomitic 
  Conglom- 
  

   erate 
  of 
  Gloucestershire 
  and 
  the 
  neighbourhood 
  of 
  the 
  Mendips 
  bears 
  

   to 
  that 
  of 
  the 
  south-west 
  of 
  England 
  *. 
  

  

  This 
  appeared 
  to 
  me 
  to 
  be 
  an 
  alternative 
  and 
  by 
  no 
  means 
  impro- 
  

   bable 
  explanation 
  of 
  the 
  facts 
  as 
  known 
  until 
  recently 
  ; 
  but 
  I 
  have, 
  

   within 
  the 
  last 
  few 
  years, 
  been 
  able 
  to 
  accumulate 
  a 
  mass 
  of 
  evidence 
  

  

  * 
  The 
  Keuper 
  breccias 
  at 
  Thringstone, 
  on 
  the 
  borders 
  of 
  Charnwoocl 
  Forest, 
  

   are 
  undoubtedly 
  marginal 
  deposits 
  of 
  this 
  kind. 
  They 
  are 
  composed 
  of 
  angular 
  

   fragments 
  derived 
  from 
  the 
  adjacent 
  Forest-rocks. 
  

  

  b2 
  

  

  