﻿Vol. 
  53.] 
  FAUNA 
  OP 
  THE 
  KEISLEY 
  LIMESTONE. 
  101 
  

  

  much 
  regularity 
  or 
  allow 
  themselves 
  to 
  be 
  traced 
  far 
  laterally, 
  but 
  

   the 
  greatest 
  development 
  of 
  the 
  dark 
  bituminous, 
  poorly 
  fossiliferous 
  

   variety 
  is 
  found 
  in 
  the 
  large 
  quarry 
  on 
  the 
  hillside, 
  which 
  is 
  still 
  

   worked. 
  This 
  quarry 
  lies 
  at 
  the 
  foot 
  of 
  the 
  hill, 
  and 
  shows 
  a 
  

   southerly 
  to 
  south-easterly 
  dip 
  of 
  these 
  beds. 
  On 
  the 
  higher 
  slopes 
  

   the 
  grey, 
  pink, 
  or 
  coarsely 
  crystalline 
  varieties 
  are 
  met 
  with, 
  but 
  

   whether 
  they 
  lie 
  above 
  or 
  below 
  the 
  bituminous 
  variety 
  is 
  doubtful. 
  

  

  The 
  red-staining 
  of 
  some 
  parts 
  of 
  the 
  limestone 
  is 
  undoubtedly 
  

   due 
  to 
  a 
  comparatively 
  recent 
  oxidation 
  of 
  the 
  contained 
  iron, 
  or 
  

   possibly 
  to 
  the 
  infiltration 
  of 
  chalybeate 
  waters. 
  

  

  The 
  patchy 
  manner 
  in 
  which 
  some 
  of 
  the 
  varieties 
  of 
  limestone 
  

   occur, 
  even 
  in 
  the 
  same 
  hand-specimen, 
  seems 
  to 
  point 
  to 
  original 
  

   slight 
  differences 
  in 
  the 
  deposit 
  or 
  to 
  segregation 
  at 
  local 
  centres 
  

   while 
  the 
  calcareous 
  mud 
  was 
  soft. 
  This 
  ' 
  patchiness 
  ' 
  is 
  espe- 
  

   cially 
  noticeable 
  in 
  the 
  case 
  of 
  the 
  fine-grained 
  pink 
  variety 
  of 
  the 
  

   limestone. 
  

  

  Some 
  of 
  the 
  minute 
  structural 
  features 
  are 
  due 
  to 
  the 
  dynamic 
  

   agencies 
  which 
  have 
  affected 
  the 
  rock. 
  

  

  Evidence 
  of 
  Disturbance. 
  

  

  Direct 
  evidence 
  of 
  considerable 
  mechanical 
  disturbance 
  of 
  the 
  

   limestone 
  is 
  afforded 
  by 
  the 
  twisted 
  wisps 
  of 
  shales 
  included 
  in 
  the 
  

   mass, 
  as 
  Marr 
  ik 
  Nicholson 
  have 
  remarked 
  (loc. 
  cit.). 
  In 
  the 
  old 
  

   disused 
  quarry, 
  south 
  of 
  the 
  one 
  now 
  worked, 
  there 
  may 
  be 
  seen 
  

   a 
  section 
  of 
  a 
  partially 
  overturned 
  fold, 
  and 
  of 
  what 
  appears 
  to 
  be 
  

   a 
  thrust-plane, 
  with 
  considerable 
  shattering 
  and 
  crushing 
  of 
  the 
  

   rock 
  along 
  the 
  gliding-surface. 
  

  

  Marr 
  & 
  Nicholson 
  believe 
  that 
  the 
  limestone 
  has 
  been 
  thickened 
  

   by 
  the 
  thrusting-up 
  together 
  of 
  the 
  calcareous 
  portions 
  and 
  

   squeezing-out 
  of 
  the 
  shaly 
  layers 
  by 
  the 
  action 
  of 
  a 
  force 
  acting 
  

   from 
  the 
  south-west, 
  and 
  they 
  mention 
  that 
  inversion 
  of 
  some 
  of 
  

   the 
  beds 
  appears 
  indicated 
  by 
  the 
  occurrence 
  of 
  Illceni 
  with 
  their 
  

   convex 
  surfaces 
  downward. 
  We 
  must 
  in 
  fact 
  regard 
  the 
  so-called 
  

   Keisley 
  Limestone 
  as 
  a 
  series 
  of 
  thin 
  limestone-bands 
  separated 
  by 
  

   thinner 
  shaly 
  layers, 
  which 
  have 
  been 
  folded, 
  crushed 
  together, 
  and 
  

   forced 
  over 
  each 
  other 
  so 
  as 
  to 
  present 
  a 
  spurious 
  thickness. 
  

  

  Stratigraphical 
  Considerations. 
  

  

  Since 
  we 
  are 
  led 
  to 
  regard 
  the 
  thickness 
  of 
  the 
  Keisley 
  Limestone 
  

   as 
  largely 
  due 
  to 
  mechanical 
  deformation 
  and 
  not 
  entirely 
  to 
  

   original 
  deposition, 
  and 
  the 
  obscurity 
  of 
  its 
  relations 
  as 
  due 
  to 
  its 
  

   isolation 
  by 
  faults, 
  we 
  might 
  not 
  unnaturally 
  think 
  that 
  it 
  was 
  a 
  

   block 
  of 
  the 
  neighbouring 
  strata 
  squeezed 
  up 
  and 
  displaced. 
  This 
  

   view, 
  however, 
  is 
  seen 
  to 
  be 
  utterly 
  untenable 
  when 
  we 
  ascertain 
  

   the 
  unique 
  facies 
  of 
  the 
  fauna 
  and 
  its 
  dissimilarity 
  to 
  that 
  of 
  any 
  

   other 
  British 
  beds 
  (see 
  infra). 
  There 
  is, 
  however, 
  an 
  idea, 
  which 
  

   at 
  first 
  sight 
  appears 
  probable, 
  that 
  the 
  Keisley 
  Limestone 
  is 
  the 
  

   sole 
  remnant 
  of 
  what 
  was 
  once 
  a 
  widespread 
  formation, 
  which 
  

  

  