﻿PROF. 
  C. 
  LAPWORTH 
  OX 
  THE 
  GIRYAN 
  SUCCESSION. 
  

  

  bQ\ 
  

  

  limestone-yielding 
  conditions 
  for 
  a 
  time 
  into 
  the 
  era 
  of 
  production 
  

   of 
  the 
  conglomerate 
  itself. 
  These 
  nodular 
  beds 
  succeed 
  a 
  patch 
  

   of 
  calcareous 
  shales 
  (Ab 
  4 
  ) 
  representative 
  of 
  the 
  Didymograptus- 
  

   beds, 
  which 
  contain 
  a 
  few 
  characteristic 
  fossils, 
  principally 
  Lingulidae. 
  

   This 
  zone 
  is 
  irregularly 
  underlain 
  by 
  the 
  compact 
  and 
  nodular 
  

   limestones, 
  which 
  are 
  exposed 
  in 
  a 
  small 
  side 
  quarry, 
  and 
  are, 
  

   especially 
  in 
  their 
  lower 
  portions, 
  greatly 
  contorted 
  and 
  shattered. 
  

   The 
  section 
  is 
  terminated 
  below 
  by 
  a 
  series 
  of 
  sandy 
  grits, 
  probably 
  

   those 
  of 
  the 
  lower 
  zones 
  of 
  the 
  O.-confinis-beds. 
  They 
  afforded 
  me 
  

   no 
  fossils, 
  but 
  they 
  present 
  the 
  hollows 
  and 
  seams 
  of 
  rottenstone 
  

   characteristic 
  of 
  the 
  zone. 
  

  

  In 
  the 
  succeeding 
  runnels 
  which 
  cross 
  the 
  prolongation 
  of 
  the 
  

   limestone 
  band 
  to 
  the 
  eastward, 
  the 
  calcareous 
  and 
  conglomeratic 
  

   groups 
  are 
  shown 
  in 
  a 
  more 
  or 
  less 
  shattered 
  condition. 
  The 
  Benan 
  

   Conglomerate 
  (Ac) 
  occupies 
  the 
  higher 
  parts 
  of 
  the 
  stream-courses. 
  

   It 
  is 
  underlain 
  in 
  the 
  natural 
  order 
  by 
  patches 
  of 
  the 
  limestone 
  beds, 
  

   which 
  in 
  their 
  turn 
  are 
  supported 
  by 
  fragments 
  of 
  the 
  under- 
  

   lying 
  sandy 
  gritstones. 
  The 
  rapidity 
  with 
  which 
  the 
  higher 
  zones 
  

   of 
  the 
  limestones 
  part 
  with 
  their 
  calcareous 
  matter 
  as 
  we 
  pass 
  to 
  

   the 
  eastward 
  is 
  most 
  remarkable, 
  the 
  whole 
  of 
  the 
  upper 
  beds 
  

   showing 
  a 
  tendency 
  to 
  degenerate 
  into 
  a 
  group 
  of 
  nodular 
  shales. 
  

  

  2. 
  Craigwells 
  or 
  Brockloch 
  Quarries. 
  — 
  After 
  traversing 
  a 
  short 
  

   interval 
  devoid 
  of 
  rock-exposures, 
  we 
  again 
  meet 
  with 
  the 
  calcareous 
  

   band 
  in 
  a 
  group 
  of 
  old 
  limestone- 
  quarries 
  lying 
  to 
  the 
  east 
  of 
  the 
  

   farmhouse 
  of 
  Brockloch. 
  

  

  In 
  the 
  quarry 
  situated 
  at 
  the 
  disused 
  limekiln 
  of 
  Craigwells 
  we 
  

   have 
  the 
  following 
  section 
  (fig. 
  5). 
  

  

  Fig. 
  5. 
  — 
  Brockloch 
  Quarry. 
  

   N.w. 
  S.E. 
  

  

  \<* 
  

  

  Ac. 
  Benan 
  Conglomerate. 
  

  

  Abe. 
  Conglomerate 
  with 
  nodules 
  

  

  of 
  lime. 
  

   Ab 
  3 
  . 
  Compact 
  Limestone, 
  20 
  feet. 
  

  

  Ab 
  2 
  . 
  Impure 
  flaggy 
  Limestones. 
  

   Ab 
  1 
  . 
  Nodular 
  Limestones. 
  

   Aa 
  2 
  . 
  Calcareous 
  Flagstone. 
  

  

  To 
  judge 
  from 
  this 
  section, 
  it 
  would 
  appear, 
  at 
  first 
  sight, 
  that 
  the 
  

   Compact 
  Limestones 
  (Ab 
  3 
  ) 
  are 
  surmounted 
  immediately 
  by 
  the 
  basal 
  

   beds 
  of 
  the 
  Benan 
  Conglomerate 
  (Ac), 
  while 
  the 
  Didymograpttus-be&s 
  

   (Ab 
  4 
  ) 
  are 
  absent 
  from 
  the 
  section, 
  having 
  apparently 
  been 
  eroded, 
  

   and 
  that 
  the 
  overlying 
  conglomerate 
  rests 
  unconformably 
  upon 
  an 
  

   undulated 
  face 
  of 
  the 
  Compact 
  Limestone, 
  fragments 
  of 
  which 
  occur 
  

  

  