﻿newton 
  : 
  gkological 
  zones 
  and 
  their 
  molldsca. 
  301 
  

  

  Formations. 
  Zones 
  of 
  Fossils. 
  

  

  TJppEu 
  (iRKENSAND 
  . 
  . 
  OrhitoUnd 
  concava. 
  

  

  Exogyra 
  digitata. 
  

  

  E. 
  columla. 
  

  

  Janira 
  quadricostata. 
  

  

  Peeten 
  orhicidaris. 
  

  

  Exogyra 
  conica. 
  

  

  E. 
  Icevigata. 
  

  

  Gault 
  Inoceramus 
  sulcatus, 
  

  

  (Blackdown 
  Beds.) 
  Exogyra 
  conica 
  (small 
  var.). 
  

  

  The 
  classic 
  memoir 
  of 
  Dr. 
  Charles 
  Barrois 
  ' 
  on 
  the 
  Upper 
  Cretaceous 
  

   deposits 
  of 
  England 
  and 
  Ireland 
  appeared 
  in 
  1876. 
  This 
  autlior 
  was 
  

   of 
  opinion 
  that 
  previous 
  descriptions 
  of 
  the 
  Chalk 
  deposits 
  of 
  Great 
  

   Britain 
  were 
  somewhat 
  inadequate, 
  and 
  he 
  therefore 
  submitted 
  a 
  

   detailed 
  account 
  of 
  the 
  distribution 
  of 
  the 
  beds 
  observed 
  in 
  tlie 
  

   various 
  areas 
  of 
  the 
  South 
  of 
  England, 
  Norfolk, 
  Lincolnshire, 
  Yoik- 
  

   shire, 
  and 
  ^Northern 
  Ireland. 
  He 
  utilized 
  zonal 
  subdivisions, 
  adopting 
  

   those 
  proposed 
  by 
  Hebert 
  ^ 
  in 
  his 
  scheme 
  of 
  the 
  Cretaceous 
  deposits 
  of 
  

   the 
  Paris 
  Basin 
  region 
  of 
  France. 
  The 
  faunas 
  were 
  also 
  compared 
  

   with 
  those 
  of 
  jN^orth-'West 
  Germany 
  ; 
  whilst 
  the 
  Irish 
  Chalk 
  lie 
  

   regarded 
  as 
  belonging 
  to 
  zones 
  included 
  in 
  the 
  Cenomanian, 
  Turonian, 
  

   and 
  Senouian 
  horizons 
  of 
  the 
  Upper 
  Cretaceous; 
  and 
  so 
  resembling 
  in 
  

   this 
  wa}' 
  similarly 
  aged 
  deposits 
  of 
  England. 
  

  

  The 
  zones 
  adopted 
  by 
  Barrois 
  were 
  based 
  on 
  five 
  Echinoderms, 
  one 
  

   Brachiopod, 
  and 
  five 
  had 
  their 
  index-fossils 
  selected 
  from 
  the 
  molluscan 
  

   group 
  of 
  organisms. 
  

  

  / 
  Zone 
  of 
  BeJemnitella 
  mucronata. 
  

   c 
  ' 
  ,, 
  J\[armpites 
  oniatus. 
  

  

  iSENONIAN 
  < 
  " 
  nr- 
  , 
  

  

  i 
  ,, 
  Micraster 
  corangmnum. 
  

   \ 
  ,, 
  M. 
  cortestudinarium. 
  

   I 
  , 
  , 
  Iloldster 
  planus. 
  

   Turonian 
  |' 
  ,, 
  Ter 
  eh' 
  atulma 
  gracilis. 
  

   \ 
  ,, 
  Inoceramiis 
  labiatiis. 
  

   , 
  , 
  Belemnites 
  plenus. 
  

   ,, 
  Ilulaster 
  suhghhosus. 
  

   Cenomanian 
  / 
  Chloritic 
  Marl. 
  

  

  Zone 
  of 
  Peeten 
  asper. 
  

  

  ,, 
  Ammonites 
  inflatus. 
  

  

  An 
  excellent 
  piece 
  of 
  zoning 
  work 
  was 
  accomplished 
  by 
  Mr. 
  Henry 
  

   Woods 
  ^ 
  some 
  years 
  since 
  in 
  connexion 
  with 
  the 
  MoUusca 
  of 
  the 
  

   ' 
  Chalk 
  Bock 
  ', 
  which 
  was 
  a 
  deposit 
  so 
  named 
  by 
  Mr. 
  Whitaker,* 
  who 
  

  

  ^ 
  " 
  Eecherches 
  snr 
  le 
  Terrain 
  Cretace 
  superieur 
  de 
  I'Angleterre 
  et 
  de 
  I'Irlande 
  " 
  : 
  

  

  Mem. 
  Soc. 
  geol. 
  Nord 
  [Lille], 
  1876, 
  pp. 
  234, 
  maps 
  and 
  sections. 
  Ann. 
  See. 
  

  

  geol. 
  Nord 
  [Lille], 
  vol. 
  iii, 
  p. 
  190, 
  1876. 
  

   "- 
  Bull. 
  Soc. 
  geol. 
  France, 
  published 
  mostly 
  in 
  the 
  seventies. 
  

   ''' 
  Quart. 
  .Journ. 
  Geol. 
  8oc., 
  vol. 
  Iii, 
  pis. 
  ii-iv, 
  pp. 
  68-98, 
  1896 
  ; 
  vol. 
  liii, 
  

  

  pis. 
  xxvii-xxviii, 
  pp. 
  .377-404, 
  1897. 
  

   * 
  Catalogue 
  of 
  B,ock-speciviens 
  in 
  the 
  Museum 
  of 
  Practical 
  Geology, 
  2nd 
  ed., 
  

  

  p. 
  296, 
  1860; 
  Quart. 
  .Journ. 
  Geol. 
  Soc, 
  vol. 
  xvii, 
  p. 
  166, 
  1861. 
  

  

  