﻿574 
  PROF. 
  C. 
  LAPWORTH 
  ON 
  THE 
  GIRVAN 
  SUCCESSION. 
  

  

  exposed 
  are 
  impure 
  calcareous 
  flagstones 
  (Ab 
  2 
  ). 
  These 
  are 
  greatly- 
  

   shattered 
  and 
  crushed 
  by 
  the 
  fault, 
  and 
  weather 
  down 
  into 
  small 
  

   irregularly 
  shaped 
  fragments, 
  which, 
  upon 
  the 
  dissolution 
  of 
  their 
  in- 
  

   cluded 
  calcareous 
  matter, 
  subside 
  into 
  a 
  black 
  mud. 
  They 
  are 
  

   actually 
  thin-bedded 
  limestone-flags, 
  with 
  a 
  wrinkled, 
  pitted 
  surface, 
  

   the 
  irregularities 
  of 
  which 
  are 
  filled 
  up 
  with 
  soft 
  dark 
  mud 
  of 
  a 
  

   flaky 
  texture. 
  They 
  yield 
  many 
  examples 
  of 
  Maclurea 
  Logani 
  of 
  

   large 
  size, 
  together 
  with 
  myriads 
  of 
  the 
  minute 
  crustacean 
  Cythere 
  

   aldensis, 
  M'Coy. 
  It 
  is 
  difficult 
  to 
  estimate 
  the 
  thickness 
  of 
  these 
  

   Maclurea-fl.ELgstones, 
  but 
  it 
  cannot 
  be 
  less 
  than 
  30 
  or 
  40 
  feet. 
  

  

  They 
  are 
  succeeded 
  by 
  the 
  Compact 
  Limestone 
  beds 
  in 
  thick 
  

   strata, 
  clearly 
  identical 
  with 
  the 
  Compact 
  Limestones 
  of 
  Benan 
  

   Burn. 
  No 
  reliable 
  estimate 
  can 
  be 
  formed 
  of 
  their 
  original 
  thick- 
  

   ness 
  at 
  this 
  locality, 
  but 
  it 
  must 
  have 
  been 
  somewhat 
  less 
  than 
  that 
  

   of 
  the 
  subjacent 
  flagstones. 
  

  

  At 
  the 
  east 
  end 
  of 
  the 
  quarry 
  a 
  fault 
  has 
  brought 
  down 
  the 
  

   more 
  gently 
  inclined 
  Benan 
  Conglomerate 
  against 
  these 
  Compact 
  

   Limestones 
  ; 
  but 
  as 
  we 
  trace 
  the 
  fault 
  in 
  its 
  course 
  along 
  the 
  face 
  

   of 
  the 
  quarry 
  to 
  the 
  west, 
  some 
  of 
  the 
  intermediate 
  beds 
  make 
  

   their 
  appearance 
  below 
  it. 
  These 
  consist 
  of 
  thin-bedded 
  greenish- 
  

   grey 
  shales 
  of 
  some 
  ten 
  or 
  twelve 
  feet 
  in 
  thickness, 
  clearly 
  repre- 
  

   sentative 
  of 
  our 
  Didymograptus-hedis 
  of 
  the 
  Kirkdominae 
  band 
  and 
  

   the 
  corresponding 
  zone 
  of 
  Craigwells 
  (Ab 
  4 
  ). 
  They 
  are 
  here 
  abun- 
  

   dantly 
  fossiliferous, 
  being 
  crowded 
  with 
  casts 
  of 
  fossils 
  of 
  the 
  genera 
  

   Agnostus, 
  Illcenus, 
  Remopleurides, 
  Lingida, 
  Acrotreta, 
  and 
  L&ptcena, 
  

   together 
  with 
  Cythere 
  and 
  fragments 
  of 
  Encrinites. 
  The 
  remaining 
  

   quarries 
  of 
  this 
  locality 
  are 
  opened 
  along 
  the 
  southern 
  line 
  of 
  fault, 
  

   where 
  the 
  calcareous 
  series 
  is 
  seen 
  in 
  contact 
  with 
  the 
  igneous 
  rocks, 
  

   but 
  too 
  greatly 
  shattered 
  to 
  afford 
  fossils. 
  

  

  It 
  would 
  be 
  superfluous 
  to 
  point 
  out 
  how 
  easily 
  the 
  succession 
  in 
  

   this 
  locality 
  is 
  interpreted 
  b} 
  r 
  the 
  facts 
  we 
  have 
  already 
  obtained 
  

   in 
  the 
  Benan-Hill 
  area, 
  and 
  how 
  complete 
  is 
  the 
  identity 
  of 
  the 
  

   various 
  zones 
  of 
  strata 
  as 
  here 
  exhibited 
  with 
  the 
  corresponding 
  

   rocks 
  of 
  the 
  typical 
  calcareous 
  band 
  of 
  Auch 
  ensoul 
  and 
  Minuntion. 
  

   The 
  inferiority 
  of 
  the 
  Stinchar 
  calcareous 
  series 
  to 
  the 
  Benan 
  Con- 
  

   glomerate 
  and 
  the 
  natural 
  arrangement 
  of 
  the 
  members 
  of 
  that 
  

   series 
  having 
  now 
  been 
  satisfactorily 
  determined, 
  we 
  turn 
  with 
  the 
  

   confidence 
  born 
  of 
  certainty 
  to 
  the 
  study 
  of 
  the 
  remaining 
  exposures 
  

   of 
  these 
  beds 
  in 
  the 
  Girvan 
  district, 
  treating 
  of 
  each 
  exposure 
  as 
  

   briefly 
  as 
  is 
  consistent 
  with 
  the 
  object 
  we 
  have 
  in 
  view. 
  

  

  The 
  great 
  fault 
  in 
  the 
  southern 
  quarries 
  at 
  Aldons 
  is 
  well 
  shown 
  

   in 
  the 
  railway-cutting 
  above 
  Pinmore 
  Bridge. 
  Hefre 
  a 
  few 
  feet 
  of 
  

   the 
  Compact 
  Limestones 
  are 
  seen 
  in 
  a 
  shattered 
  condition 
  between 
  

   the 
  metamorphic 
  or 
  igneous 
  rock 
  and 
  the 
  overlying 
  sheet 
  of 
  Benan 
  

   Conglomerate, 
  the 
  whole 
  dipping 
  at 
  a 
  gentle 
  angle 
  to 
  the 
  north- 
  

   west. 
  

  

  The 
  same 
  fault 
  is 
  seen 
  in 
  the 
  Stinchar 
  near 
  Pinmore 
  Bridge 
  ; 
  but 
  

   there 
  is 
  no 
  trace 
  of 
  the 
  limestone. 
  

  

  Several 
  exposures 
  of 
  the 
  calcareous 
  series 
  occur, 
  however, 
  in 
  the 
  

   prolongation 
  of 
  this 
  line 
  to 
  the 
  north-west. 
  In 
  the 
  heights 
  to 
  the 
  

  

  