﻿PROP. 
  C. 
  LAPWORTH 
  ON 
  THE 
  GIRVAN 
  SUCCESSION. 
  643 
  

  

  If 
  the 
  Graptolitiferous 
  striped 
  shales 
  of 
  Shalloch 
  Forge 
  are, 
  as 
  I 
  

   have 
  already 
  argued, 
  the 
  highest 
  visible 
  beds 
  of 
  these 
  Craigskelly 
  

   rocks, 
  the 
  analogy 
  furnished 
  by 
  the 
  structure 
  of 
  the 
  area 
  already 
  

   studied 
  would 
  lead 
  us 
  to 
  infer 
  that 
  the 
  band 
  of 
  Woodland 
  limestone 
  

   which 
  lies 
  upon 
  the 
  opposite 
  margin 
  of 
  the 
  band 
  along 
  the 
  line 
  of 
  the 
  

   great 
  fault 
  must 
  be 
  the 
  lowest 
  visible 
  zone 
  of 
  the 
  series 
  as 
  here 
  

   exhibited. 
  

  

  It 
  is 
  not 
  wholly 
  impossible, 
  however, 
  that 
  the 
  rocks 
  of 
  this 
  reef 
  

   are 
  actually 
  arranged 
  in 
  the 
  anticlinal 
  form 
  suggested 
  by 
  the 
  di- 
  

   verging 
  dips 
  upon 
  the 
  opposite 
  margins. 
  If 
  so, 
  the 
  Woodland 
  

   limestone 
  would 
  form 
  part 
  of 
  the 
  Coralline 
  lime-band 
  of 
  the 
  Horse 
  

   Rock 
  and 
  the 
  "Woodland 
  grits, 
  being 
  lost 
  in 
  the 
  fault 
  at 
  the 
  base 
  

   of 
  that 
  limestone, 
  a 
  part 
  of 
  them 
  only 
  being 
  seen 
  upon 
  the 
  north- 
  

   western 
  flanks 
  of 
  Craigskelly, 
  while 
  the 
  boulder-band 
  of 
  the 
  Horse 
  

   Eock 
  would 
  then 
  form 
  the 
  lowest 
  bed 
  of 
  the 
  series. 
  But 
  the 
  pre- 
  

   sence 
  of 
  the 
  soft 
  Graptolitic 
  mudstones 
  between 
  the 
  Woodland 
  

   limestone 
  and 
  the 
  Scart 
  grits, 
  the 
  similarity 
  of 
  the 
  basement-beds 
  

   of 
  the 
  latter 
  to 
  the 
  quartz 
  conglomerate 
  of 
  Shalloch 
  Forge, 
  together 
  

   with 
  the 
  general 
  correspondence 
  in 
  petrological 
  characters 
  of 
  the 
  

   Scart 
  grits 
  and 
  those 
  of 
  Saugh 
  Hill, 
  all 
  concur 
  to 
  favour 
  the 
  

   theory 
  of 
  the 
  general 
  identity 
  of 
  the 
  Woodland 
  limestone 
  and 
  the 
  

   Coralline 
  band. 
  In 
  this 
  case 
  the 
  sequence 
  of 
  the 
  Newlands 
  Series 
  

   along 
  the 
  shore-line 
  will 
  stand 
  as 
  follows 
  : 
  — 
  

  

  Cbb. 
  Saugh-Hill 
  / 
  2. 
  Scart 
  Grits 
  and 
  Flagstones, 
  

   beds. 
  [ 
  1. 
  Quartz 
  conglomerate. 
  

  

  {4. 
  Grey 
  non-fossiliferous 
  shales 
  of 
  Penwhapple. 
  

   3. 
  Striped 
  and 
  black 
  Graptolite-shales 
  and 
  mudstones. 
  

   2. 
  Woodland 
  Limestone. 
  

   1. 
  Craigskelly 
  Boulder-conglomerate. 
  

  

  On 
  this 
  view 
  we 
  are 
  able 
  to 
  reconcile 
  several 
  important 
  physical 
  

   facts 
  obtainable 
  within 
  the 
  Girvan 
  region. 
  

  

  (1) 
  At 
  the 
  south-eastern 
  extremity 
  of 
  the 
  Horse 
  Rock, 
  where 
  the 
  

   Craigskelly 
  boulder-bed 
  is 
  seen 
  in 
  contact 
  with 
  the 
  underlying 
  

   green 
  flagstones 
  and 
  shales, 
  there 
  is 
  a 
  distinct 
  appearance 
  of 
  uncon- 
  

   forniability, 
  the 
  coarse 
  boulder-beds 
  resting 
  upon 
  the 
  slightly 
  eroded 
  

   faces 
  of 
  the 
  older 
  beds. 
  

  

  (2) 
  On 
  the 
  north-western 
  flank 
  of 
  Saugh 
  Hill 
  a 
  boulder-conglo- 
  

   merate, 
  probably 
  identical 
  with 
  that 
  of 
  Craigskelly, 
  rests 
  at 
  once 
  

   upon 
  the 
  Barren 
  Flagstones 
  of 
  Cuddystone 
  Burn 
  (see 
  fig. 
  25). 
  

  

  (3) 
  The 
  united 
  thickness 
  of 
  the 
  Woodland 
  and 
  Saugh-Hill 
  sub- 
  

   formations, 
  thus 
  arranged, 
  agrees 
  closely 
  with 
  that 
  of 
  their 
  repre- 
  

   sentatives, 
  the 
  coarse 
  conglomerates 
  and 
  yellow 
  flagstones 
  of 
  New- 
  

   lands 
  and 
  Craigwells, 
  in 
  the 
  northern 
  inlier. 
  

  

  (4) 
  An 
  uncouformability 
  at 
  the 
  base 
  of 
  the 
  Craigskelly 
  conglo- 
  

   merate 
  rids 
  us 
  of 
  the 
  necessity 
  for 
  assuming 
  the 
  presence 
  of 
  the 
  

   Drummuck 
  and 
  Mulloch-Hill 
  formations 
  south 
  of 
  the 
  Girvan 
  valley, 
  

   and 
  thus 
  reduces 
  the 
  theoretical 
  downthrow 
  of 
  the 
  Saugh-Hill 
  and 
  

   Woodland 
  faults 
  to 
  comparative 
  insignificance. 
  

  

  