﻿634 
  

  

  PX0F. 
  C. 
  LAPWOKTH 
  ON 
  THE 
  G1F.VAN 
  SUCCESSION. 
  

  

  Bastrites 
  peregriuus, 
  Barr. 
  

  

  hybridus, 
  Lapw. 
  

  

  Monograptus 
  Sedgwicki, 
  Portl. 
  

   Hisingeri, 
  Carr. 
  

  

  Monograptus 
  interniedius, 
  Carr. 
  

  

  spiralis, 
  His. 
  

  

  Diplograptus 
  folium, 
  His. 
  

  

  palmeus, 
  Barr. 
  

  

  Hughesii, 
  Nich. 
  

  

  The 
  soft 
  black 
  mudstones 
  terminate 
  abruptly 
  to 
  the 
  north 
  against 
  

   the 
  series 
  of 
  grits 
  and 
  sandstones 
  which 
  form 
  our 
  datum-zone 
  of 
  the 
  

   Pentamerus-he&s 
  of 
  Camregan. 
  

  

  Our 
  study 
  of 
  the 
  Graptolitic 
  shales 
  and 
  gritstones 
  of 
  Penwhapple 
  

   have 
  thus 
  resulted 
  in 
  showing 
  us 
  that 
  in 
  this 
  locality 
  there 
  are 
  two 
  

   distinct 
  Graptolitiferous 
  zones, 
  one 
  at 
  each 
  end 
  of 
  the 
  section 
  — 
  the 
  

   earlier 
  one 
  characterized 
  by 
  Diplograptus 
  modestus, 
  Lapw., 
  and 
  a 
  

   few 
  other 
  forms, 
  and 
  the 
  later 
  one 
  by 
  Monograptus 
  Sedgivic7cii, 
  Portl., 
  

   and 
  its 
  usual 
  associates. 
  These 
  two 
  terminal 
  zones 
  are 
  here 
  divided 
  

   from 
  each 
  other 
  by 
  an 
  intermediate 
  zone 
  of 
  barren 
  pale-hearted 
  

   and 
  pebbly 
  gritstone. 
  

  

  The 
  M. 
  Sedgwickii 
  bed 
  at 
  the 
  summit 
  of 
  the 
  section 
  is 
  clearly 
  absent 
  

   from 
  the 
  Glenshalloch 
  area 
  ; 
  nor 
  is 
  there 
  any 
  thing 
  in 
  that 
  district 
  

   we 
  can 
  satisfactorily 
  parallel 
  with 
  the 
  central 
  grits 
  and 
  shales 
  of 
  Pen- 
  

   whapple. 
  The 
  only 
  strata, 
  therefore, 
  that 
  we 
  may 
  regard 
  as 
  possibly 
  

   common 
  to 
  our 
  Glenshalloch 
  and 
  Penwhapple 
  sections 
  are 
  the 
  grey 
  

   shales 
  of 
  the 
  first 
  zone 
  ; 
  and 
  even 
  of 
  these 
  the 
  black 
  Z), 
  modestus 
  mud- 
  

   stones 
  at 
  their 
  base 
  are 
  unseen 
  in 
  the 
  northern 
  inlier. 
  

  

  If, 
  therefore, 
  the 
  JNewlands 
  Pentamerus-gTits 
  which 
  underlie 
  

   the 
  main 
  mass 
  of 
  the 
  Glenshalloch 
  shales, 
  conglomerates, 
  and 
  

   limestones 
  are 
  present 
  in 
  the 
  southern 
  area, 
  we 
  can 
  only 
  expect 
  to 
  

   find 
  them 
  in 
  the 
  immediate 
  neighbourhood 
  of 
  the 
  Saugh-Hill 
  fault. 
  

  

  (b) 
  Confirmatory 
  Section 
  of 
  Sough 
  Hill. 
  

  

  Eastward 
  of 
  Penwhapple 
  Glen 
  no 
  good 
  sections 
  of 
  these 
  strata 
  

   are 
  visible 
  ; 
  but 
  westward 
  their 
  beds 
  are 
  greatly 
  developed 
  and 
  are 
  

   fairly 
  exhibited 
  to 
  the 
  investigator. 
  

  

  Saugh-Hill 
  area 
  (Diplograptus-modestiis 
  Shales). 
  — 
  Excellent 
  sec- 
  

   tions 
  of 
  the 
  basal 
  zone 
  of 
  grey 
  shales 
  are 
  seen 
  in 
  the 
  Tralorg 
  Burn. 
  

   The 
  inverted 
  beds 
  dip 
  with 
  tolerable 
  regularity 
  towards 
  the 
  line 
  of 
  

   the 
  Saugh-Hill 
  fault 
  ; 
  but 
  we 
  find 
  evidence 
  that 
  the 
  great 
  dislo- 
  

   cation 
  crosses 
  different 
  horizons 
  along 
  its 
  course, 
  in 
  the 
  presence 
  of 
  

   soft 
  white 
  mudstones 
  and 
  shales 
  which 
  are 
  unknown 
  in 
  the 
  Pen- 
  

   whapple 
  section 
  ; 
  while 
  occasional 
  bosses 
  of 
  a 
  coarse 
  pebbly 
  conglome- 
  

   rate 
  are 
  found 
  along 
  the 
  same 
  line. 
  

  

  As 
  the 
  line 
  of 
  grey 
  shales 
  is 
  followed 
  over 
  the 
  higher 
  ground 
  to 
  the 
  

   west, 
  the 
  section 
  beeomes 
  obscured 
  by 
  vegetation, 
  and 
  we 
  find 
  no 
  

   exposure 
  of 
  the 
  Diplograptus-modestus 
  band 
  until 
  we 
  reach 
  the 
  head 
  

   of 
  Saughill 
  Burn, 
  more 
  than 
  a 
  mile 
  to 
  the 
  westward, 
  where 
  the 
  many 
  

   small 
  drains 
  afford 
  a 
  few 
  insignificant 
  exposures. 
  

  

  On 
  the 
  west 
  side 
  of 
  Saughill 
  Burn, 
  at 
  the 
  precise 
  point 
  where 
  the 
  

   Saugh-Hill 
  fault 
  is 
  cut 
  off 
  by 
  a 
  transverse 
  dislocation, 
  a 
  good 
  section 
  

   of 
  the 
  Graptolite-bearing 
  beds 
  of 
  a 
  part 
  of 
  the 
  grey-shale 
  band 
  is 
  shown 
  

   in 
  the 
  miniature 
  cliffs 
  by 
  the 
  side 
  of 
  the 
  almost 
  obliterated 
  hill-road. 
  

   Here 
  dark 
  carbonaceous 
  shales 
  dip 
  into 
  the 
  Saugh-Hill 
  fault 
  at 
  a 
  

  

  