﻿Vol. 
  53.] 
  THE 
  PORTE4INE 
  INLIER 
  (CO. 
  DUBLIN). 
  529 
  

  

  the 
  end 
  of 
  the 
  point 
  south 
  of 
  the 
  Old 
  Limekiln. 
  Here 
  thin-bedded 
  

   limestones 
  with 
  shaly 
  partings 
  ccme 
  on 
  again 
  below 
  the 
  compacter 
  

   bed, 
  and, 
  as 
  might 
  be 
  expected, 
  tbe 
  signs 
  of 
  disturbance 
  become 
  

   more 
  marked, 
  the 
  thin 
  bands 
  of 
  limestone 
  being 
  often 
  crushed 
  so 
  as 
  

   to 
  form 
  what 
  look 
  like 
  bands 
  of 
  nodules 
  or 
  pebbles 
  embedded 
  in 
  

   shale, 
  while 
  excellent 
  examples 
  of 
  overfolding 
  may 
  be 
  seen 
  (see 
  

   fig. 
  1). 
  At 
  the 
  head 
  of 
  the 
  bay, 
  south-west 
  of 
  the 
  Limekiln, 
  the 
  

   limestone 
  is 
  traversed 
  by 
  two 
  or 
  more 
  faults 
  aud 
  shows 
  signs 
  of 
  

   much 
  disturbance 
  ; 
  but 
  at 
  the 
  western 
  end 
  of 
  this 
  bay 
  the 
  beds 
  

   are 
  undisturbed, 
  and 
  consist 
  of 
  thin 
  regular 
  bands 
  of 
  limestone 
  

   alternating 
  with 
  shales. 
  

  

  Eesting 
  upon 
  these 
  limestones 
  and 
  shales 
  we 
  again 
  find 
  the 
  

   compact 
  limestone, 
  which 
  is 
  here 
  very 
  hard 
  and 
  forms 
  a 
  prominent 
  

   rampart-like 
  mass 
  at 
  the 
  top 
  of 
  the 
  cliff. 
  This 
  bed 
  and 
  the 
  under- 
  

   lying 
  shaly 
  limestone 
  occupy 
  the 
  coast 
  as 
  far 
  as 
  the 
  next 
  point, 
  and 
  

   it 
  is 
  along 
  here 
  that 
  the 
  limestone 
  has 
  proved 
  most 
  fossiliferous. 
  A 
  

   small 
  quarry 
  has 
  been 
  opened 
  at 
  the 
  top 
  of 
  the 
  cliff 
  in 
  the 
  compact 
  

   limestone, 
  at 
  the 
  spot 
  marked 
  C 
  in 
  the 
  map 
  (PI. 
  XLIII), 
  and 
  from 
  

   it 
  we 
  obtained 
  the 
  fossils 
  enumerated 
  in 
  the 
  Appendix 
  (p. 
  535). 
  

   Of 
  these, 
  Cheirurus 
  bhmicronatus, 
  Pseudosplicerexochus 
  subquadratvs, 
  

   Sjphcerexochus 
  minis, 
  Cybele 
  rugosa, 
  Trinucleus 
  seticornis, 
  and 
  Stauro- 
  

   cephalus 
  are 
  worth 
  mentioning 
  here. 
  A 
  portion 
  of 
  this 
  limestone 
  

   was 
  dissolved 
  in 
  acid, 
  and 
  4*3 
  per 
  cent, 
  of 
  it 
  was 
  insoluble 
  : 
  this 
  

   residue, 
  when 
  examined 
  under 
  the 
  microscope, 
  being 
  seen 
  to 
  consist 
  

   chiefly 
  of 
  small 
  pieces 
  of 
  pumice 
  and 
  a 
  little 
  pyrites. 
  

  

  The 
  limestones 
  interbedded 
  with 
  shales 
  are 
  at 
  this 
  spot 
  crowded 
  

   with 
  corals, 
  excellent 
  specimens 
  of 
  which, 
  weathered 
  out 
  by 
  the 
  

   sea, 
  were 
  readily 
  procured. 
  Holy 
  'sites 
  catenularia 
  and 
  Heliolites 
  

   megastoma 
  were 
  the 
  most 
  numerous 
  forms, 
  and 
  a 
  complete 
  list 
  is 
  given 
  

   in 
  the 
  Appendix. 
  Prom 
  the 
  abundance 
  of 
  coral 
  life 
  which 
  existed 
  

   here 
  one 
  is 
  justified 
  in 
  regarding 
  this 
  as 
  a 
  coral 
  bank. 
  

  

  The 
  next 
  small 
  bay 
  is 
  divided 
  into 
  two 
  by 
  a 
  tongue 
  of 
  rock, 
  through 
  

   the 
  landward 
  end 
  of 
  which 
  the 
  sea 
  has 
  forced 
  a 
  passage. 
  The 
  signs 
  

   of 
  disturbance 
  here 
  are 
  very 
  great 
  indeed. 
  The 
  more 
  northerly 
  

   of 
  the 
  two 
  little 
  bays 
  shows 
  interbedded 
  shale- 
  and 
  limestone-bands, 
  

   all 
  much 
  crushed, 
  the 
  rock 
  showing 
  an 
  excellent 
  overfold 
  at 
  one 
  

   place. 
  The 
  Point 
  is 
  also 
  formed 
  of 
  these 
  much-crushed 
  limestones, 
  

   the 
  bands 
  being 
  so 
  much 
  broken 
  and 
  the 
  resulting 
  fragments 
  so 
  

   much 
  rounded 
  as 
  to 
  form 
  a 
  crush-conglomerate, 
  this 
  being 
  especially 
  

   well 
  seen 
  below 
  high-water 
  mark 
  on 
  the 
  south-western 
  side 
  of 
  the 
  

   tongue 
  of 
  land 
  mentioned 
  above. 
  

  

  Here, 
  too, 
  a 
  compact 
  grey 
  limestone 
  is 
  seen 
  underlying 
  the 
  shaly 
  

   limestone, 
  but 
  it 
  did 
  not 
  prove 
  fossiliferous. 
  

  

  The 
  more 
  southerly 
  of 
  the 
  two 
  portions 
  of 
  the 
  small 
  bay 
  is 
  cut 
  

   into 
  much 
  disturbed 
  beds 
  of 
  limestone 
  and 
  shale, 
  but 
  at 
  its 
  south- 
  

   western 
  boundary 
  the 
  compact 
  limestone 
  again 
  comes 
  on, 
  being 
  

   separated 
  from 
  the 
  limestone 
  and 
  shale 
  by 
  a 
  wedge-shaped 
  mass 
  of 
  

   a 
  conglomerate 
  formed 
  of 
  limestone-pebbles, 
  all 
  much 
  rounded, 
  in 
  

   a 
  calcareous 
  matrix 
  — 
  obviously 
  a 
  conglomerate 
  due 
  to 
  earth-move- 
  

   ments. 
  

  

  Q.J.G.S. 
  No. 
  212. 
  2x 
  

  

  