﻿PROP. 
  C. 
  LAPWORTH 
  ON 
  THE 
  GIRT 
  AN 
  SUCCESSION. 
  

  

  605 
  

  

  as 
  deduced 
  from 
  their 
  exhibition 
  along 
  the 
  shore-line 
  

  

  tigator 
  (fig. 
  18) 
  : 
  and 
  the 
  evidence 
  it 
  affords 
  him 
  of 
  the 
  arrangement 
  

   of 
  the 
  component 
  strata, 
  and 
  of 
  the 
  numerous 
  folds 
  and 
  dislocations 
  

   which 
  have 
  affected 
  them, 
  is 
  invaluable. 
  

  

  (1) 
  Ba. 
  ArdweU 
  Flags 
  and 
  Shales. 
  — 
  For 
  the 
  upper 
  two 
  miles 
  of 
  

   its 
  course 
  the 
  glen 
  has 
  been 
  excavated 
  in 
  the 
  flaggy 
  rocks 
  of 
  the 
  

   Ardmillan 
  group. 
  \fe 
  have 
  here 
  therefore 
  an 
  excellent 
  oppor- 
  

   tunity 
  of 
  testing 
  the 
  accuracy 
  of 
  our 
  interpretation 
  of 
  the 
  sequence 
  

   of 
  these 
  strata 
  

   of 
  Shalloch 
  and 
  Ardwell. 
  

  

  The 
  section 
  of 
  the 
  Sen 
  an 
  Conglomerate 
  and 
  the 
  succeeding 
  Bal- 
  

   clatchie 
  Beds, 
  as 
  displayed 
  at 
  the 
  commencement 
  of 
  the 
  Penwhapple 
  

   gorge 
  to 
  the 
  north-west, 
  has 
  been 
  already 
  described 
  (p. 
  249 
  et 
  seep). 
  

  

  Lying 
  immediately 
  upon 
  the 
  ashy 
  grits 
  of 
  the 
  upper 
  zone 
  of 
  the 
  

   Balclatchie 
  Beds, 
  we 
  find 
  the 
  basal 
  strata 
  (Ba 
  1 
  of 
  fig. 
  18) 
  of 
  the 
  

   Graptolitic 
  series. 
  They 
  consist 
  of 
  masses 
  of 
  dark 
  shales 
  and 
  thin- 
  

   bedded 
  flagstones. 
  The 
  shales 
  are 
  more 
  or 
  less 
  carbonaceous, 
  

   weather 
  throughout 
  to 
  a 
  rusty-iron 
  colour, 
  and 
  are 
  clearly 
  identical 
  

   in 
  all 
  essentials 
  with 
  the 
  lower 
  Ardwell 
  beds 
  that 
  lie 
  upon 
  the 
  con- 
  

   glomerate 
  of 
  Kennedy's 
  Pass. 
  Beds 
  of 
  the 
  same 
  general 
  character 
  

   extend 
  down 
  the 
  glen, 
  and 
  are 
  magnificently 
  displayed 
  in 
  its 
  rocky 
  

   floor 
  and 
  steep 
  cliffs, 
  for 
  a 
  distance 
  of 
  about 
  a 
  quarter 
  of 
  a 
  mile, 
  

   until 
  we 
  reach 
  the 
  first 
  of 
  a 
  series 
  of 
  massive 
  green 
  and 
  more 
  or 
  

   less 
  pebbly 
  grits, 
  over 
  which 
  the 
  waters 
  of 
  the 
  burn 
  plunge 
  in 
  two 
  

   fine 
  cascades. 
  

  

  If 
  the 
  dips 
  are 
  to 
  be 
  relied 
  upon, 
  the 
  first 
  group 
  of 
  Ardwell 
  strata 
  

   between 
  the 
  Balclatchie 
  Beds 
  and 
  the 
  cascades 
  are 
  generally 
  arranged 
  

   in 
  a 
  broad 
  synclinal 
  form. 
  Several 
  distinct 
  subdivisions 
  are 
  recog- 
  

   nizable 
  as 
  at 
  Ardwell. 
  The 
  lower 
  division 
  (Ba 
  1 
  of 
  fig. 
  18) 
  consists 
  

   of 
  thin-bedded, 
  striped, 
  iron-stained 
  shales, 
  containing 
  many 
  

   Graptolites 
  in 
  certain 
  zones. 
  The 
  commonest 
  forms 
  are 
  : 
  — 
  

  

  Diplograptu3 
  foliaceus, 
  Murch. 
  

  

  rugosus, 
  Emm. 
  

  

  CHuiacograptusScliavenbergi,i(rpw. 
  

  

  Climacograptus 
  cselatus, 
  Lapw. 
  

   Corynoides 
  calycularis, 
  Nick. 
  

   Dicellograptus 
  moffatense 
  ? 
  Carr 
  

  

  Here, 
  however, 
  the 
  shales 
  contain 
  several 
  bands 
  of 
  cement-stone, 
  

   which 
  yield 
  a 
  few 
  Brachiopocla. 
  Nodules 
  of 
  calcareous 
  matter, 
  too, 
  

   are 
  frequent. 
  These 
  contain 
  some 
  fine 
  examples 
  of 
  Orthoceratites, 
  

   an 
  occasional 
  shell, 
  and 
  fragments 
  of 
  sponge-spicules. 
  

  

  From 
  these 
  beds 
  have 
  been 
  procured 
  at 
  various 
  times 
  by 
  former 
  

   investigators, 
  by 
  Mrs. 
  Gray, 
  by 
  Mr. 
  M'Fie 
  of 
  the 
  neighbouring 
  estate 
  

   of 
  Rnockgerran, 
  or 
  by 
  myself, 
  the 
  following 
  characteristic 
  forms 
  : 
  — 
  

  

  Orthoceras 
  angulatum, 
  Wahl. 
  

   calarniteuui, 
  Miinst. 
  

  

  Orthoceras 
  politum, 
  M'Coy. 
  

   Hyalonema 
  girvauense, 
  Kick. 
  

  

  This 
  basal 
  (or 
  Knockgerran) 
  zone 
  is 
  overlain 
  in 
  the 
  central 
  parts 
  of 
  

   the 
  exposure 
  by 
  a 
  more 
  flaggy 
  series 
  (Ba 
  2), 
  answering 
  to 
  the 
  more 
  

   typical 
  beds 
  of 
  the 
  coast-section. 
  Its 
  beds 
  consist 
  of 
  striped 
  flags 
  

   from 
  2 
  to 
  4 
  inches 
  in 
  thickness, 
  relieved 
  by 
  occasional 
  shale 
  seams 
  

   and 
  a 
  few 
  insignificant 
  bands 
  of 
  dark 
  grey 
  grit. 
  Above 
  follows 
  a 
  

   third 
  subdvision 
  (Ba 
  3) 
  composed 
  of 
  ironstained 
  shales, 
  similar 
  to 
  

  

  