﻿"^°^ 
  53*] 
  THE 
  CRETACEOUS 
  STRATA 
  OF 
  COUNTY 
  ANTRIM. 
  597 
  

  

  Zone 
  of 
  Belemnitella 
  \Actinocamax\ 
  vera 
  and 
  

   B. 
  [A.] 
  quadrata. 
  

  

  It 
  is 
  very 
  evident 
  that 
  it 
  was 
  during 
  the 
  period 
  of 
  these 
  two 
  

   zones 
  that 
  the 
  greater 
  part 
  of 
  Antrim 
  became 
  submerged 
  beneath 
  

   sea-level, 
  with 
  the 
  production 
  of 
  mulatto-stone 
  or 
  conglomeratic 
  

   chalk 
  in 
  the 
  Central 
  Division, 
  of 
  Spongiarian 
  beds 
  in 
  the 
  Eastern 
  

   and 
  part 
  of 
  the 
  Central 
  districts, 
  and 
  of 
  beach-deposits 
  in 
  the 
  

   Peninsular 
  area, 
  while 
  true 
  White 
  Chalk 
  was 
  already 
  being 
  

   formed 
  in 
  the 
  Northern 
  Division. 
  We 
  have 
  seen 
  that 
  Belemnitella 
  

   [Actinocamax] 
  vera 
  occurs 
  in 
  the 
  conglomerate 
  at 
  Colin 
  Glen, 
  

   in 
  the 
  Spongiarian 
  zone 
  of 
  Islandmagee, 
  and 
  in 
  the 
  white 
  lime- 
  

   stone 
  of 
  the 
  Northern 
  Division; 
  B. 
  [J..] 
  quadrata 
  (Blainv.) 
  and 
  

   B. 
  [A.~] 
  Alfridi, 
  Janet, 
  in 
  the 
  glauconitic 
  rock 
  of 
  Forth 
  River 
  ; 
  

   B. 
  [A.~\ 
  quadrata 
  and 
  Micr 
  aster 
  cor-anguinum 
  in 
  the 
  nodular 
  

   glauconitic 
  chalk 
  of 
  Squires 
  Hill 
  ; 
  and 
  B. 
  [A.~] 
  Alfridi 
  together 
  

   with 
  gasteropoda 
  in 
  the 
  beach-deposits 
  of 
  the 
  Peninsular 
  area. 
  

   These 
  zones 
  have 
  been 
  at 
  present 
  classed 
  together, 
  because 
  hitherto 
  

   the 
  two 
  zone-fossils 
  have 
  been 
  seldom 
  obtained 
  in 
  the 
  same 
  

   locality 
  ; 
  but 
  when 
  thus 
  found, 
  the 
  rule 
  usual 
  elsewhere 
  is 
  followed, 
  

   B. 
  \_A.~\ 
  vera 
  being 
  found 
  in 
  beds 
  lower 
  than 
  those 
  containing 
  

   B. 
  [A.~\ 
  quadrata. 
  

  

  The 
  principal 
  fossils 
  are 
  tabulated 
  on 
  p. 
  596. 
  The 
  fossils 
  for 
  the 
  

   Northern 
  Division 
  are 
  enumerated 
  on 
  Barrois's 
  authority 
  ; 
  those 
  

   marked 
  with 
  a 
  G 
  have 
  been 
  recorded 
  by 
  Gault 
  from 
  the 
  Central 
  

   Division. 
  

  

  Tate, 
  in 
  his 
  table, 
  places 
  the 
  Spongiarian 
  zone 
  and 
  that 
  of 
  Anan- 
  

   cliytes 
  gibbus 
  at 
  the 
  Belemnitella 
  [Actinocamax] 
  quadrata-level, 
  but 
  

   the 
  above 
  fauna 
  shows 
  that 
  these 
  are, 
  in 
  part 
  at 
  least, 
  of 
  B. 
  \_A.~\ 
  

   vera-dige. 
  Barrois 
  1 
  also 
  arrived 
  at 
  the 
  conclusion 
  that, 
  whereas 
  

   the 
  sponge-beds 
  in 
  Germany 
  are 
  mainly 
  at 
  the 
  summit 
  of 
  the 
  B. 
  

   [A] 
  quadrata-zone 
  (zone 
  of 
  BecJcsia 
  SceJcelandi, 
  of 
  Schliiter), 
  those 
  

   in 
  Ireland 
  occur 
  at 
  the 
  base 
  of 
  this 
  zone, 
  and 
  the 
  two 
  are 
  conse- 
  

   quently 
  not 
  comparable. 
  Also, 
  comparing 
  the 
  sponges 
  obtained 
  in 
  

   the 
  Spongiarian 
  zone 
  with 
  those 
  from 
  the 
  well-known 
  horizon 
  at 
  

   Danes' 
  Dyke 
  near 
  Bridlington, 
  there 
  is 
  no 
  sponge 
  common 
  to 
  the 
  

   two 
  localities. 
  Taking 
  all 
  the 
  evidence 
  together, 
  there 
  seems 
  little 
  

   doubt 
  that 
  the 
  pebble-beds, 
  mulatto-stones, 
  and 
  Spongiarian 
  beds 
  

   were 
  formed 
  mainly 
  during 
  the 
  period 
  of 
  these 
  two 
  zones, 
  the 
  

   latter 
  being 
  most 
  certainly 
  of 
  B. 
  [AJ] 
  vera-age. 
  

  

  White 
  Limestone. 
  (Zone 
  of 
  Belemnitella 
  mucronata.) 
  

  

  To 
  this 
  zone 
  belongs 
  the 
  white 
  hardened 
  limestone 
  overlying 
  the 
  

   strata 
  previously 
  described, 
  which 
  forms 
  so 
  conspicuous 
  a 
  feature 
  

   in 
  all 
  the 
  Antrim 
  divisions. 
  In 
  the 
  Southern, 
  Central 
  (Black 
  

   Mountain), 
  and 
  Peninsular 
  areas, 
  Belemnitella 
  mucronata 
  occurs 
  in 
  

   a 
  pebble-containing 
  mulatto-stone. 
  

  

  Possils. 
  — 
  General 
  : 
  Belemnitella 
  mucronata, 
  Schloth., 
  Ammonites 
  

  

  1 
  ' 
  Kecherches 
  sur 
  le 
  Terrain 
  Cretace, 
  etc.,' 
  p. 
  210 
  

  

  