﻿Vol. 
  53.] 
  THE 
  CKETACEOUS 
  STRATA 
  OE 
  COUNTY 
  ANTRIM. 
  569 
  

  

  studying 
  the 
  Cretaceous 
  zones 
  of 
  the 
  Isle 
  of 
  Wight 
  and 
  Folke- 
  

   stone. 
  1 
  

  

  Many 
  of 
  the 
  samples 
  were 
  obtained 
  at 
  Woodburn 
  Glen, 
  a 
  locality 
  

   which 
  has 
  been 
  especially 
  referred 
  to 
  by 
  both 
  Tate 
  and 
  Barrois 
  ; 
  

   while 
  from 
  Murlough 
  Bay 
  a 
  series 
  of 
  specimens 
  were 
  selected 
  

   for 
  the 
  reasons 
  mentioned 
  on 
  p. 
  565. 
  I 
  may 
  recall 
  that 
  in 
  Table 
  II. 
  

   the 
  ' 
  main 
  residue 
  ' 
  consists 
  of 
  the 
  fine 
  clayey 
  or 
  siliceous 
  materials, 
  

   the 
  ' 
  heavy 
  residue 
  ' 
  being 
  the 
  organic 
  and 
  mineral 
  contents 
  which 
  

   remain 
  after 
  the 
  clay 
  has 
  been 
  removed 
  by 
  repeated 
  washing 
  and 
  

   decantation. 
  

  

  Glauconitic 
  Sands. 
  (Zone 
  of 
  Eooogyra 
  conic 
  a.) 
  

   Woodburn 
  Glen. 
  (No. 
  7 
  in 
  Table 
  II.) 
  

  

  The 
  specimens 
  obtained 
  were 
  of 
  a 
  deep-green 
  colour, 
  and 
  con- 
  

   sisted 
  mainly 
  of 
  glauconite 
  and 
  quartz-grains 
  loosely 
  cemented 
  by 
  

   calcareous 
  material. 
  The 
  samples 
  were 
  taken 
  from 
  the 
  upper 
  part 
  

   of 
  the 
  bed, 
  consequently 
  above 
  the 
  well-known 
  fossil-band. 
  

  

  The 
  original 
  weight, 
  after 
  drying, 
  = 
  77*59 
  grammes. 
  After 
  

   solution 
  in 
  20°/ 
  hydrochloric 
  acid 
  there 
  remained 
  58*66 
  grammes. 
  

   Heavy 
  residue 
  = 
  75-6°/ 
  . 
  

  

  Total 
  composition 
  : 
  — 
  

  

  Carbonate 
  of 
  lime 
  24-4 
  ° 
  / 
  

  

  Heavy 
  residue 
  75'6 
  % 
  

  

  100 
  

  

  The 
  heavy 
  residue 
  was 
  further 
  subdivided 
  into 
  four 
  divisions 
  by 
  

   sifting, 
  namely 
  : 
  — 
  

  

  A 
  (coarse). 
  Weight 
  = 
  *45 
  gramme. 
  Mainly 
  composed 
  of 
  quartz- 
  

   grains, 
  the 
  largest 
  of 
  which 
  was 
  a 
  subangular 
  fragment 
  3*5 
  mm. 
  

   long 
  and 
  1*5 
  mm. 
  broad. 
  The 
  great 
  majority 
  of 
  these 
  are 
  water- 
  

   worn, 
  and 
  the 
  larger 
  ones 
  are 
  coloured 
  green, 
  pink, 
  or 
  yellow. 
  

   Although 
  many 
  of 
  the 
  grains 
  show 
  evidence 
  of 
  the 
  presence 
  

   of 
  crystal-faces, 
  yet 
  the 
  angles 
  are 
  much 
  worn 
  down, 
  and 
  the 
  

   smaller 
  ones, 
  averaging 
  1 
  mm. 
  in 
  diameter, 
  are 
  beautifully 
  rounded 
  

   and 
  water-clear. 
  A 
  few 
  small 
  cleavage-fragments 
  of 
  red 
  orthoclase 
  

   are 
  also 
  present, 
  the 
  largest 
  being 
  about 
  1 
  mm. 
  square. 
  

  

  B 
  (medium). 
  The 
  greater 
  proportion 
  of 
  this 
  material 
  consists 
  of 
  

   glauconite-grains 
  of 
  a 
  deep 
  blue-green 
  colour. 
  Most 
  of 
  these 
  are 
  

   undoubtedly 
  the 
  internal 
  casts 
  of 
  foraminifera, 
  the 
  numerous 
  lobes 
  

   into 
  which 
  they 
  are 
  divided 
  indicating 
  the 
  multi-chambered 
  

   character 
  of 
  the 
  genera 
  which 
  contained 
  them. 
  The 
  average 
  size 
  of 
  

   the 
  better-defined 
  examples 
  is 
  between 
  *5 
  and 
  1 
  mm. 
  As 
  a 
  rule 
  

   it 
  is 
  quite 
  impossible 
  to 
  determine 
  the 
  forms 
  generically, 
  but 
  these 
  

   may 
  be 
  differentiated 
  into 
  four 
  types 
  : 
  — 
  

  

  1. 
  Eotaline 
  types, 
  which 
  include 
  all 
  grains 
  having 
  the 
  chamber- 
  

   casts 
  rolled 
  in 
  a 
  nautiloid 
  manner, 
  but 
  with 
  the 
  earlier 
  chambers 
  

   only 
  visible 
  on 
  one 
  side. 
  These 
  are 
  very 
  numerous. 
  

  

  1 
  See 
  ' 
  Chemical 
  and 
  Micro-Mineralogical 
  Kesearches 
  on 
  the 
  Upper 
  Cre- 
  

   taceous 
  Zones 
  of 
  the 
  South 
  of 
  England/ 
  London, 
  1893, 
  pp. 
  11 
  & 
  12. 
  

  

  