﻿622 
  PROP. 
  C. 
  LA.PWOETH 
  ON 
  THE 
  GIRVAN 
  SUCCESSION. 
  

  

  are 
  succeeded 
  abruptly 
  by 
  a 
  mass 
  of 
  very 
  coarse 
  boulder-conglome- 
  

   rate, 
  which 
  forms 
  a 
  conspicuous 
  scarp 
  and 
  ridge 
  upon 
  the 
  highest 
  

   points 
  of 
  Quarrel 
  Hill, 
  and 
  ranges 
  thence 
  eastward 
  and 
  southward, 
  

   round 
  the 
  curving 
  anticlinal 
  arch. 
  

  

  This 
  peculiar 
  conglomerate 
  reminds 
  us 
  somewhat 
  of 
  the 
  massive 
  

   Benan 
  Conglomerate 
  of 
  the 
  south 
  in 
  the 
  size 
  and 
  character 
  of 
  its 
  

   included 
  pebbles. 
  These 
  are 
  of 
  quartz, 
  granite, 
  felstone, 
  and 
  

   several 
  varieties 
  of 
  igneous 
  rock. 
  The 
  matrix, 
  however, 
  is 
  of 
  a 
  dull 
  

   purplish 
  tinge, 
  and 
  is 
  in 
  truth 
  a 
  sandy 
  gritstone. 
  Its 
  grains 
  are 
  

   usually 
  well 
  rounded 
  ; 
  and 
  when 
  pebbles 
  are 
  rare 
  the 
  rock 
  degenerates 
  

   into 
  a 
  coarse 
  sandy 
  grit. 
  Tn 
  its 
  aspect 
  and 
  composition 
  the 
  rock 
  

   resembles 
  the 
  bands 
  of 
  conglomerate 
  so 
  abundant 
  among 
  the 
  Old 
  

   Red 
  Sandstone 
  rocks 
  of 
  Scotland, 
  especially 
  those 
  of 
  the 
  lower 
  di- 
  

   vision 
  of 
  that 
  peculiar 
  series. 
  It 
  is 
  distinctly 
  bedded 
  throughout 
  

   its 
  entire 
  thickness, 
  which 
  does 
  not 
  here 
  exceed 
  75 
  feet, 
  the 
  planes 
  

   of 
  deposition 
  being 
  marked 
  by 
  seams 
  of 
  sandstone, 
  lines 
  of 
  boulders, 
  

   and 
  zones 
  of 
  hard 
  grey 
  grit. 
  Towards 
  its 
  summit 
  it 
  includes 
  a 
  

   thick 
  zone 
  of 
  sandy 
  flagstone, 
  or 
  tilestone, 
  of 
  a 
  reddish 
  grey 
  tint, 
  

   containing 
  many 
  casts 
  of 
  fossils, 
  and 
  indicative 
  of 
  the 
  commencement 
  

   of 
  the 
  conditions 
  which 
  resulted 
  in 
  the 
  formation 
  of 
  the 
  overlying 
  

   masses 
  of 
  sandy 
  flagstones 
  of 
  Mulloch 
  Hill. 
  

  

  This 
  conglomerate 
  is 
  traceable 
  from 
  the 
  Craighead 
  fault 
  at 
  Glen- 
  

   lochrie, 
  through 
  the 
  faults 
  of 
  Quarrel 
  Hill, 
  into 
  the 
  valley 
  of 
  the 
  

   Lady 
  Burn, 
  and 
  thence 
  in 
  patches 
  to 
  the 
  farmhouse 
  of 
  Drummuck, 
  

   following 
  in 
  immediate 
  and 
  locally 
  conformable 
  succession 
  to 
  the 
  

   Drummuck 
  shales. 
  

  

  Scattered 
  exposures 
  of 
  similar 
  rock 
  are 
  seen 
  to 
  the 
  south-west 
  of 
  

   this, 
  as 
  near 
  Kippery 
  and 
  Woodhead 
  and, 
  finally, 
  in 
  a 
  wide 
  area 
  

   around 
  the 
  mansion 
  of 
  Trochraive. 
  Here 
  coarse 
  conglomerates 
  

   occur 
  in 
  detached 
  quarries 
  and 
  in 
  projecting 
  bosses 
  in 
  the 
  park 
  

   and 
  cultivated 
  fields. 
  These 
  certainly 
  belong 
  to 
  the 
  Mulloch-Hill 
  

   band 
  ; 
  but 
  they 
  are 
  flaggier 
  and 
  greyer, 
  and 
  have 
  hardly 
  the 
  same 
  

   characters 
  either 
  in 
  their 
  matrix 
  or 
  in 
  their 
  included 
  pebbles. 
  

  

  The 
  fossils 
  afforded 
  by 
  the 
  Mulloch-Hill 
  conglomerate, 
  in 
  the 
  

   type 
  locality 
  of 
  Quarrel 
  Hill, 
  are 
  principally 
  Brachiopoda 
  of 
  the 
  

   genera 
  Rhynchunella, 
  Orthis, 
  Leptama, 
  and 
  Strophomena, 
  identical 
  in 
  

   species 
  with 
  those 
  we 
  shall 
  find 
  to 
  be 
  characteristic 
  of 
  the 
  over- 
  

   lying 
  Mulloch-Hill 
  sandstones, 
  and 
  generally 
  distinct, 
  considered 
  as 
  

   a 
  group, 
  from 
  those 
  that 
  mark 
  the 
  immediately 
  subjacent 
  Drummuck 
  

   mudstones. 
  

  

  Indeed 
  the 
  distinction 
  in 
  physical 
  features 
  and 
  in 
  fossils 
  between 
  

   the 
  soft 
  Drummuck 
  mudstones, 
  with 
  their 
  abundant 
  examples 
  of 
  

   Trinucleus, 
  Asaphus, 
  Dionicle, 
  Ampyoc, 
  and 
  hosts 
  of 
  Bellerophon 
  &c, 
  

   and 
  these 
  overlying 
  Bi-achiopod-ssLndstones 
  is 
  most 
  striking 
  ; 
  and 
  

   we 
  find 
  here 
  the 
  grandest 
  palseontological 
  break 
  in 
  the 
  entire 
  Girvan 
  

   succession. 
  None 
  of 
  the 
  genera 
  enumerated 
  above 
  as 
  characteristic 
  

   of 
  the 
  Ardmillan 
  group 
  have 
  ever 
  yet 
  been 
  certainly 
  met 
  with 
  above 
  

   the 
  base 
  of 
  this 
  conglomerate 
  ; 
  while 
  the 
  most 
  characteristic 
  species 
  

   and 
  genera 
  of 
  Trilobita, 
  Brachiopoda, 
  and 
  Graptolithina 
  of 
  the 
  over- 
  

   lying 
  beds 
  are 
  equally 
  absent 
  from 
  the 
  Ardmillan 
  series. 
  

  

  