﻿BEER 
  HEAD 
  AND 
  THE 
  ADJACENT 
  CLIFE-SECTIONS. 
  385 
  

  

  These 
  cretaceous 
  rocks 
  of 
  Ireland 
  have 
  been 
  referred 
  by 
  Mr. 
  Tate 
  

   to 
  two 
  formations 
  — 
  " 
  the 
  Hibernian 
  Greensand, 
  and 
  the 
  Upper 
  

   Chalk," 
  the 
  term 
  "Hibernian 
  Greensand" 
  being 
  applied 
  to 
  the 
  

   cretaceous 
  beds 
  underlying 
  the 
  Upper 
  Chalk 
  of 
  Ireland. 
  

  

  The 
  Hibernian 
  series, 
  says 
  Mr. 
  Tate, 
  " 
  forms 
  three 
  lithological 
  

   zones, 
  each 
  with 
  its 
  own 
  suite 
  of 
  organic 
  remains." 
  For 
  their 
  full 
  

   description, 
  however, 
  I 
  must 
  refer 
  the 
  reader 
  to 
  the 
  original 
  paper. 
  

  

  Now, 
  of 
  these 
  three 
  zones, 
  the 
  lowest, 
  or 
  " 
  Glauconitic 
  Sands 
  " 
  of 
  

   Tate, 
  apparently 
  represents 
  to 
  some 
  extent 
  the 
  beds 
  1 
  to 
  3 
  of 
  the 
  

   Devon 
  sections. 
  

  

  The 
  succeeding 
  " 
  grey 
  marls 
  and 
  sandstones 
  with 
  chert 
  " 
  clearly 
  

   represent 
  the 
  true 
  Upper 
  Greensand, 
  in 
  part 
  (beds 
  4 
  & 
  5), 
  of 
  the 
  

   Devon 
  sections. 
  

  

  The 
  " 
  chloritic 
  sands 
  and 
  sandstones 
  " 
  forming 
  the 
  upper 
  part 
  of 
  

   the 
  Hibernian 
  Greensand 
  would 
  seem 
  by 
  some 
  of 
  their 
  fossils 
  to 
  

   represent 
  the 
  beds 
  immediately 
  beneath 
  the 
  Chloritic 
  Marl 
  (beds 
  6 
  

   to 
  9) 
  of 
  the 
  Devon 
  sections. 
  They 
  contain, 
  however, 
  apparently 
  a 
  

   singular 
  mixture 
  of 
  species, 
  and 
  are 
  consequently 
  not 
  easy 
  to 
  corre- 
  

   late. 
  And 
  the 
  same 
  must 
  be 
  said, 
  I 
  think, 
  with 
  respect 
  to 
  the 
  so- 
  

   called 
  Upper 
  Chalk. 
  

  

  IV. 
  Conclusion, 
  

  

  Taken 
  as 
  a 
  whole, 
  then, 
  and 
  in 
  spite 
  of 
  the 
  as 
  yet 
  doubtful 
  age 
  

   of 
  the 
  lowest 
  and 
  highest 
  deposits, 
  the 
  Beer-Head 
  and 
  contiguous 
  

   sections 
  of 
  the 
  Devon 
  Cretaceous 
  strata 
  present 
  collectively 
  a 
  highly 
  

   important 
  section. 
  One 
  may 
  observe 
  here, 
  as 
  probably 
  nowhere 
  

   else 
  in 
  one 
  continuous 
  section, 
  the 
  true 
  relation 
  of 
  the 
  fossiliferous 
  

   Blackdown 
  strata 
  to 
  those 
  of 
  Warminster, 
  and, 
  what 
  is 
  at 
  least 
  

   almost 
  equally 
  important, 
  the 
  relation 
  of 
  both 
  of 
  these 
  beds 
  to 
  that 
  

   of 
  the 
  true 
  Upper 
  Greensand 
  of 
  the 
  Isle 
  of 
  "Wight. 
  

  

  The 
  " 
  Blackdown 
  beds 
  " 
  in 
  these 
  sections 
  underlie 
  most 
  clearly 
  

   the 
  true 
  Upper 
  Greensand, 
  and 
  hold 
  (apparently) 
  the 
  position 
  of 
  the 
  

   Gault 
  or 
  of 
  the 
  Gault 
  and 
  Upper 
  Keocomian 
  in 
  part. 
  

  

  The 
  "Warminster 
  beds," 
  on 
  the 
  contrary, 
  are 
  seen 
  to 
  cap 
  the 
  

   Upper 
  Greensand, 
  and 
  are 
  therefore 
  in 
  reality 
  Chloritic 
  Marl. 
  

  

  If, 
  then, 
  the 
  above 
  should 
  prove 
  to 
  be 
  a 
  correct 
  reading 
  of 
  these 
  

   Devon 
  sections, 
  it 
  cannot 
  but 
  affect 
  to 
  some 
  extent 
  the 
  use 
  of 
  the 
  

   term 
  Upper 
  Greensand 
  ; 
  and 
  I 
  submit 
  that 
  such 
  term 
  should 
  be 
  

   applied 
  exclusively, 
  as 
  far 
  as 
  possible, 
  to 
  beds 
  between 
  the 
  Gault 
  

   and 
  the 
  Chloritic 
  Marl, 
  and 
  that 
  the 
  Chloritic 
  Marl 
  should 
  be 
  con- 
  

   sidered 
  a 
  distinct 
  division. 
  

  

  