﻿610 
  PKOF. 
  C. 
  LAPWOETH 
  ON 
  THE 
  GIKVAN 
  SUCCESSION. 
  

  

  In 
  these 
  scattered 
  exposures, 
  more 
  especially 
  in 
  one 
  small 
  quarry 
  

   about 
  one 
  third 
  of 
  a 
  mile 
  north 
  of 
  Mickle 
  Letterpin, 
  certain 
  grey 
  

   and 
  striped 
  shales 
  represent 
  the 
  transitional 
  band 
  at 
  the 
  base 
  of 
  the 
  

   Ardwell 
  group. 
  From 
  these 
  I 
  have 
  procured, 
  among 
  others 
  : 
  — 
  

  

  Dicranograptus 
  spinifer. 
  Lapw. 
  

   Dicellograptus, 
  sp. 
  

   Leptograptus 
  flaccid 
  us, 
  var. 
  (3. 
  

  

  Diplograptus 
  foliaceus, 
  Murch. 
  

   Cryptograptus 
  tricornis, 
  Carr. 
  

  

  Cliinacograptus 
  bieornis, 
  Hall. 
  

  

  Scbarenbergi. 
  Lapw. 
  

  

  Ortbis 
  ActoniaB. 
  

   Leptaena 
  tenuistriata. 
  

  

  Similar 
  beds 
  may 
  be 
  followed 
  at 
  intervals 
  over 
  the 
  entire 
  area 
  of 
  this 
  

   district 
  as 
  marked 
  upon 
  the 
  map 
  (PI. 
  XXIY.). 
  In 
  the 
  hollows 
  between 
  

   we 
  see 
  the 
  typical 
  dark 
  blue 
  or 
  grey 
  and 
  more 
  or 
  less 
  striped 
  shales 
  

   of 
  Ardwell, 
  Aveathering 
  to 
  their 
  typical 
  rusty-brown 
  colour 
  — 
  here 
  

   hardened 
  and 
  barren, 
  there 
  softer 
  and 
  affording 
  a 
  few 
  Graptolites, 
  

   always 
  of 
  the 
  species 
  of 
  the 
  shore. 
  Along 
  the 
  line 
  of 
  the 
  southern 
  

   conglomerate 
  many 
  of 
  the 
  beds 
  are 
  inverted 
  and 
  highly 
  indurated. 
  

   The 
  presence 
  of 
  the 
  soft 
  yellow 
  sandy 
  conglomerates 
  of 
  the 
  Balclat- 
  

   chie 
  Beds 
  along 
  the 
  line 
  of 
  the 
  fault 
  to 
  the 
  north 
  renders 
  the 
  west 
  

   boundary 
  of 
  the 
  beds 
  in 
  that 
  direction 
  more 
  obscure. 
  

  

  The 
  recurrence 
  of 
  similar 
  mineralogical 
  zones 
  of 
  strata 
  in 
  the 
  

   series 
  as 
  developed 
  in 
  this 
  extended 
  area, 
  though 
  the 
  group, 
  as 
  a 
  

   whole, 
  apparently 
  dips 
  steadily 
  to 
  the 
  northward, 
  makes 
  it 
  certain 
  

   that 
  the 
  numerous 
  inverted 
  folds 
  and 
  accompanying 
  faults, 
  apparent 
  

   on 
  the 
  flanks 
  of 
  Daldowie 
  Hill, 
  are 
  prolonged 
  into 
  the 
  Pinmore 
  area 
  ; 
  

   and 
  to 
  these 
  are 
  due 
  the 
  monotonous 
  character 
  and 
  great 
  apparent 
  

   thickness 
  of 
  the 
  beds. 
  

  

  2. 
  Exposures 
  East 
  and 
  West 
  of 
  Penwhapple 
  Glen 
  — 
  The 
  section 
  we 
  

   have 
  described 
  in 
  Penwhapple 
  Glen 
  is 
  typical 
  of 
  the 
  structure 
  of 
  the 
  

   entire 
  area 
  occupied 
  by 
  the 
  Ardmillan 
  group 
  between 
  the 
  Penan 
  

   Conglomerate 
  and 
  the 
  great 
  fault 
  of 
  Saugh 
  Hill, 
  south 
  of 
  a 
  straight 
  

   line 
  ranging 
  from 
  the 
  Dow 
  Hill 
  across 
  the 
  region 
  into 
  the 
  faulted 
  

   area 
  of 
  Dalamford, 
  on 
  the 
  terrace 
  of 
  Straiton 
  and 
  Garleffm. 
  This 
  

   entire 
  district 
  is 
  floored 
  with 
  repetitions 
  of 
  the 
  various 
  subordinate 
  

   members 
  of 
  the 
  Ardwell 
  Beds. 
  The 
  varying 
  lines 
  of 
  strike 
  are 
  all 
  

   clearly 
  dependent 
  upon 
  the 
  general 
  outline 
  of 
  the 
  mass 
  of 
  Benan 
  

   Conglomerate, 
  which 
  everywhere 
  underlies 
  these 
  rocks 
  around 
  the 
  

   broad 
  curve 
  forming 
  the 
  southern 
  and 
  eastern 
  limits 
  of 
  the 
  area 
  from 
  

   Balclatchie 
  to 
  Piedmont. 
  The 
  strata 
  are 
  clearly 
  more 
  or 
  less 
  folded 
  

   and 
  faulted 
  throughout 
  : 
  but 
  the 
  general 
  similarity 
  of 
  the 
  beds 
  from 
  

   bottom 
  to 
  top 
  of 
  the 
  series, 
  and 
  the 
  scanty 
  exposures 
  within 
  the 
  

   area, 
  do 
  not 
  allow 
  us 
  to 
  offer 
  more 
  than 
  a 
  general 
  idea 
  of 
  the 
  

   arrangement 
  of 
  the 
  strata. 
  

  

  The 
  finest 
  sections 
  to 
  the 
  southward 
  are 
  seen 
  around 
  the 
  Barbae 
  

   Hill 
  near 
  Tramitchell, 
  where 
  the 
  fossiliferous 
  Barbae 
  Grit 
  is 
  seen 
  

   to 
  be 
  surmounted 
  by 
  soft 
  dark 
  shales 
  of 
  the 
  Lower 
  Ardwell 
  

   beds, 
  containing 
  a 
  few 
  shells 
  and 
  Graptolites 
  in 
  the 
  intercalated 
  

   cement-stones 
  and 
  conglomerate 
  bands, 
  and 
  passing 
  upwards 
  into 
  a 
  

   great 
  thickness 
  of 
  hard 
  flaggy 
  gritstones, 
  separated 
  by 
  the 
  usual 
  

   rusty 
  and 
  striped 
  carbonaceous 
  shales. 
  These 
  shales 
  and 
  overlying 
  

   flags 
  sweep 
  in 
  a 
  continuous 
  curve, 
  2| 
  miles 
  in 
  length, 
  from 
  Tra- 
  

  

  