﻿244 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [Mar. 
  23, 
  

  

  to 
  the 
  dip, 
  the 
  observer 
  can 
  often, 
  from 
  some 
  commanding 
  point, 
  

   trace 
  out 
  the 
  geological 
  structure 
  of 
  the 
  country 
  around 
  by 
  the 
  aid 
  

   of 
  its 
  surface- 
  configuration 
  alone. 
  

  

  In 
  order 
  to 
  determine 
  with 
  accuracy 
  the 
  relationship 
  to 
  each 
  other 
  

   of 
  the 
  different 
  beds 
  which 
  form 
  the 
  escarpments 
  of 
  the 
  district, 
  

   we 
  began, 
  with 
  the 
  express 
  wish 
  of 
  Prof. 
  Ramsay, 
  to 
  trace 
  out 
  

   separately 
  each 
  bed 
  of 
  grit, 
  from 
  the 
  base 
  of 
  the 
  Lower 
  Coal-mea- 
  

   sures 
  downwards; 
  hoping 
  that, 
  in 
  a 
  country 
  where 
  the 
  features 
  

   were 
  so 
  obvious 
  and 
  so 
  seldom 
  hidden 
  by 
  drift, 
  we 
  should 
  be 
  able 
  to 
  

   ascertain, 
  with 
  certainty, 
  the 
  range 
  of 
  each 
  bed, 
  and 
  note 
  the 
  changes 
  

   in 
  its 
  thickness 
  and 
  quality, 
  which 
  previous 
  observation, 
  and 
  the 
  

   description 
  by 
  Prof. 
  Phillips 
  of 
  the 
  grits 
  in 
  the 
  neighbouring 
  district 
  

   of 
  Yorkshire, 
  led 
  us 
  to 
  look 
  for 
  *. 
  Mr. 
  Binney 
  has 
  endeavoured, 
  

   with 
  much 
  success, 
  to 
  identify 
  the 
  grits 
  and 
  coal-seams 
  of 
  Lan- 
  

   cashire 
  and 
  parts 
  of 
  Derbyshire 
  ; 
  while 
  Farey 
  had, 
  with 
  wonderful 
  

   diligence 
  and 
  judgment, 
  attempted 
  the 
  same 
  feat 
  many 
  years 
  ago; 
  

   but, 
  except 
  by 
  tracing 
  each 
  band 
  of 
  grit 
  step 
  by 
  step, 
  it 
  was 
  impos- 
  

   sible 
  for 
  any 
  one, 
  however 
  sagacious, 
  to 
  feel 
  sure 
  as 
  to 
  the 
  identity, 
  

   at 
  points 
  widely 
  distant 
  from 
  each 
  other, 
  of 
  beds 
  parted 
  by 
  faults 
  

   and 
  changed 
  in 
  look 
  by 
  the 
  changes 
  in 
  quality 
  to 
  which 
  sandstones 
  

   are 
  liable. 
  

  

  We 
  now 
  propose 
  to 
  begin 
  with 
  the 
  Millstone-grit 
  as 
  it 
  is 
  seen 
  on 
  

   the 
  borders 
  of 
  Lancashire 
  and 
  South 
  Yorkshire, 
  and 
  to 
  describe 
  a 
  

   series 
  of 
  sections 
  taken 
  at 
  intervals 
  over 
  the 
  district 
  from 
  north 
  to 
  

   south, 
  which 
  will 
  serve 
  to 
  show 
  a 
  general 
  thinning 
  away 
  of 
  the 
  series 
  

   towards 
  the 
  south 
  or 
  south-west. 
  The 
  general 
  attenuation 
  of 
  the 
  

   sedimentary 
  rocks 
  of 
  the 
  Carboniferous 
  series 
  in 
  this 
  direction 
  has 
  

   been 
  pointed 
  out 
  by 
  one 
  of 
  the 
  authors 
  in 
  a 
  former 
  paper 
  f. 
  The 
  pre- 
  

   sent 
  has 
  for 
  its 
  object 
  to 
  give 
  the 
  details 
  for 
  the 
  Millstone-grit 
  over 
  

   a 
  small 
  definite 
  tract 
  of 
  country. 
  

  

  § 
  2. 
  Loiver 
  Coal-measures, 
  and 
  Upper 
  Limit 
  of 
  the 
  Millstone-grit. 
  

  

  Before 
  entering 
  on 
  our 
  immediate 
  subject 
  it 
  will 
  be 
  advisable 
  to 
  

   give 
  a 
  short 
  description 
  of 
  the 
  overlying 
  Carboniferous 
  rocks, 
  so 
  as 
  

   to 
  define 
  clearly 
  what 
  we 
  take 
  to 
  be 
  the 
  upper 
  limit 
  of 
  the 
  Millstone- 
  

   The 
  Coal-measures 
  of 
  Lancashire 
  are 
  divisible 
  into 
  three 
  stages, 
  

   namely, 
  

  

  The 
  Tipper, 
  consisting 
  of 
  purple 
  and 
  grey 
  shales 
  and 
  sandstones 
  

   with 
  thin 
  beds 
  of 
  limestone 
  and 
  coal. 
  Thickness, 
  2000 
  feet. 
  

  

  The 
  Middle. 
  Prom 
  the 
  Pendleton 
  Four-foot 
  down 
  to 
  the 
  Arley 
  

   Mine, 
  or 
  a 
  little 
  lower 
  ; 
  they 
  consist 
  of 
  shales 
  and 
  sandstones, 
  and 
  

   contain 
  all 
  the 
  thick 
  coals. 
  Thickness, 
  3000 
  feet. 
  

  

  The 
  Lower 
  or 
  Gannister 
  beds. 
  From 
  the 
  Arley 
  Mine 
  to 
  the 
  

   Rough 
  Rock; 
  they 
  consist 
  of 
  micaceous 
  sandstones 
  and 
  shales, 
  

   with 
  three 
  or 
  four 
  thin 
  beds 
  of 
  coal. 
  Thickness, 
  1800 
  feet. 
  

   The 
  coals 
  of 
  the 
  Lower 
  Measures 
  are, 
  in 
  descending 
  order 
  : 
  

   1st. 
  The 
  Forty 
  Yards 
  Mine, 
  known 
  at 
  Up-Holland, 
  Chorley, 
  

  

  * 
  Geology 
  of 
  Yorkshire, 
  Part 
  2, 
  1836, 
  pp. 
  58 
  et 
  seq. 
  

  

  t 
  Hull, 
  " 
  On 
  Isometric 
  Lines, 
  &c," 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  voLxviii. 
  p. 
  127. 
  

  

  