﻿636 
  TEOF. 
  C. 
  LAPWOETH 
  OX 
  THE 
  GIEVAX 
  SUCCESSION". 
  

  

  intervene 
  to 
  separate 
  the 
  grey-shale 
  zone 
  from 
  the 
  M.-Sedgwichii 
  

   mudstones. 
  

  

  The 
  yellow 
  grits, 
  imitating 
  precisely 
  in 
  the 
  gentle 
  cnrvatnre 
  of 
  

   their 
  strike 
  the 
  range 
  of 
  the 
  grey 
  shales 
  to 
  the 
  south, 
  sweep 
  np 
  

   from 
  the 
  banks 
  of 
  Penwhapple 
  into 
  the 
  hill 
  of 
  Camregan, 
  forming 
  a 
  

   broad 
  and 
  well-marked 
  mound 
  upon 
  the 
  surface 
  of 
  the 
  ground. 
  

   Thence 
  they 
  are 
  followed 
  continuously 
  along 
  the 
  ridge 
  into 
  the 
  

   summit 
  of 
  Saugh 
  Hill, 
  forming 
  a 
  broad 
  mound-like 
  ridge, 
  from 
  700 
  

   to 
  900 
  feet 
  in 
  height 
  and 
  more 
  than 
  two 
  miles 
  in 
  length, 
  which 
  

   looks 
  down 
  upon 
  Girvan 
  and 
  the 
  cultivated 
  slopes 
  of 
  the 
  Brae. 
  At 
  

   its 
  eastern 
  extremity 
  the 
  extent 
  of 
  surface 
  floored 
  with 
  this 
  band 
  of 
  

   coarse 
  grits 
  is 
  not 
  more 
  than 
  300 
  feet 
  in 
  width 
  ; 
  but 
  as 
  it 
  pro- 
  

   ceeds 
  to 
  the 
  eastwards, 
  it 
  rapidly 
  enlarges 
  its 
  diameter, 
  till 
  finally, 
  

   upon 
  the 
  summit 
  of 
  Saugh 
  Hill 
  (fig. 
  2-5 
  ), 
  it 
  cannot 
  be 
  less 
  than 
  600 
  feet 
  

   wide 
  : 
  and 
  the 
  group 
  attains 
  here 
  a 
  geographical 
  importance 
  which 
  

   has 
  suggested 
  to 
  me 
  the 
  title 
  of 
  Saughr-HiU 
  Group 
  as 
  the 
  collective 
  

   name 
  for 
  the 
  entire 
  Gritstone 
  and 
  Graptolitiferous 
  series. 
  

  

  The 
  coarse 
  grits 
  are 
  exposed 
  in 
  a 
  host 
  of 
  quarries 
  and 
  natural 
  

   sections 
  along 
  the 
  ridge 
  ; 
  and 
  much 
  additional 
  knowledge 
  of 
  the 
  

   physical 
  characteristics 
  of 
  the 
  group 
  is 
  obtainable. 
  In 
  addition 
  to 
  

   the 
  coarse 
  and 
  more 
  or 
  less 
  flaggy 
  gritstones 
  of 
  Penwhapple 
  Glen, 
  

   we 
  have 
  here 
  actual 
  beds 
  of 
  conglomerates 
  with 
  pebbles 
  an 
  inch 
  or 
  

   two 
  in 
  diameter 
  and 
  peculiar 
  breccias 
  made 
  up 
  of 
  angular 
  fragments 
  

   of 
  quartz, 
  gritstones 
  and 
  shales, 
  imbedded 
  in 
  a 
  strange 
  matrix 
  of 
  a 
  

   greyish-white 
  colour. 
  Some 
  of 
  the 
  associated 
  grits 
  are 
  of 
  great 
  

   thickness, 
  but 
  are 
  generally 
  separable 
  into 
  large 
  parallel 
  flags. 
  The 
  

   entire 
  group 
  is 
  very 
  sandy 
  in 
  character 
  ; 
  the 
  majority 
  of 
  the 
  beds 
  

   weather 
  to 
  an 
  orange-yellow, 
  and 
  occasionally 
  even 
  to 
  a 
  faint 
  pink 
  

   colour. 
  Fossils 
  are 
  said 
  to 
  have 
  been 
  procured 
  from 
  these 
  beds 
  ; 
  

   but 
  I 
  have 
  never 
  yet 
  been 
  able 
  to 
  detect 
  a 
  single 
  fragment 
  of 
  any- 
  

   thing 
  organic 
  within 
  them. 
  

  

  The 
  great 
  width 
  of 
  the 
  band 
  upon 
  Saugh 
  Hill 
  is 
  undoubtedly 
  due 
  

   to 
  the 
  fact 
  that 
  the 
  beds 
  are 
  repeatedly 
  folded. 
  A 
  peculiar 
  rock, 
  

   having 
  the 
  general 
  character 
  of 
  a 
  bastard 
  limestone, 
  makes 
  its 
  

   appearance 
  again 
  and 
  again 
  as 
  we 
  cross 
  the 
  band 
  transversely, 
  and 
  

   affords 
  a 
  good 
  idea 
  of 
  the 
  number 
  of 
  hidden 
  folds. 
  

  

  The 
  narrow 
  diameter 
  of 
  the 
  same 
  zone 
  near 
  Penwhapple 
  is 
  in 
  all 
  

   probability 
  due 
  to 
  faulting, 
  as 
  there 
  are 
  certainly 
  several 
  strata 
  

   upon 
  Saugh 
  Hill 
  that 
  are 
  wanting 
  in 
  our 
  Penwhapple 
  section. 
  

  

  Monof/raptus-Sedgu)ic7cii 
  Mudstones. 
  — 
  Between 
  the 
  summit 
  of 
  the 
  

   Saugh-Hill 
  ridge, 
  which 
  is 
  occupied 
  by 
  the 
  yellow 
  grits 
  and 
  sand- 
  

   stones 
  described, 
  and 
  the 
  general 
  datum-line 
  of 
  the 
  axial 
  Camregan 
  

   limestone 
  group, 
  few 
  sections 
  are 
  visible 
  : 
  but 
  all 
  the 
  evidences 
  they 
  

   afford 
  us 
  concur 
  to 
  prove 
  that 
  this 
  interesting 
  band 
  of 
  country 
  is 
  

   mainly 
  occupied 
  by 
  the 
  final 
  or 
  M.-Sedgwiclii 
  band 
  of 
  the 
  Saugh-Hill 
  

   group. 
  The 
  second 
  grit 
  of 
  Penwhapple 
  cannot 
  be 
  traced 
  for 
  any 
  great 
  

   distance 
  westwards 
  ; 
  and 
  its 
  place 
  is 
  occupied 
  by 
  dark 
  shales, 
  appa- 
  

   rently 
  of 
  the 
  M.-Sedgwiclcii 
  zone, 
  within 
  a 
  quarter 
  of 
  a 
  mile 
  of 
  the 
  

   glen. 
  Grey 
  flaggy 
  shales 
  similar 
  to 
  those 
  in 
  contact 
  with 
  these 
  grits 
  

   are 
  traceable 
  bounding 
  the 
  Saugh-Hill 
  sandstones 
  along 
  the 
  northern 
  

  

  