﻿572 
  DR. 
  W. 
  ERASER 
  HUME 
  ON 
  [Dec. 
  1 
  89 
  7, 
  

  

  Zircon 
  is 
  present 
  in 
  very 
  rounded 
  grains, 
  many 
  of 
  which 
  are 
  

   distinctly 
  zoned. 
  Maximum 
  length 
  "056 
  mm., 
  breadth 
  *026 
  mm. 
  

  

  Iron 
  Pyrites 
  is 
  abundant 
  in 
  rods, 
  rounded- 
  aggregates, 
  and 
  

   thin 
  films, 
  and 
  limonite 
  is 
  also 
  not 
  uncommon. 
  

  

  As 
  previously 
  mentioned, 
  flakes 
  of 
  silvery 
  muscovite 
  and 
  

   brown 
  biotite 
  are 
  numerous, 
  in 
  addition 
  to 
  green 
  micaceous 
  films 
  

   of 
  chlorite. 
  

  

  Garnet. 
  A 
  very 
  transparent 
  mineral, 
  having 
  perfect 
  crystalline 
  

   form 
  (rhombic 
  dodecahedron) 
  and 
  quite 
  isotropic, 
  agrees 
  in 
  its 
  

   characters 
  with 
  the 
  crystals 
  which 
  have 
  been 
  definitely 
  determined 
  

   in 
  the 
  next 
  zone. 
  

  

  Kyanite. 
  A 
  rectangular 
  block 
  with 
  feebly-developed 
  pinacoidal 
  

   cleavages 
  at 
  90°, 
  polarizing 
  in 
  low 
  grey 
  tints 
  and 
  having 
  an 
  ex- 
  

   tinction 
  angle 
  of 
  30°, 
  is 
  evidently 
  an 
  example 
  of 
  this 
  mineral. 
  

  

  As 
  in 
  the 
  previous 
  cases, 
  opaque 
  white 
  and 
  dull 
  brown 
  adamantine 
  

   grains 
  are 
  numerous, 
  but 
  their 
  true 
  nature 
  has 
  not 
  been 
  determined. 
  

  

  A 
  second 
  experiment 
  carried 
  out 
  on 
  42*45 
  grammes 
  of 
  material 
  

   yielded 
  : 
  

  

  Carbonate 
  of 
  lime 
  70-32% 
  

  

  Eesidue 
  29-68% 
  

  

  100 
  

   While 
  the 
  marl 
  was 
  dissolving 
  a 
  delicate 
  foraminifer 
  was 
  

   obtained, 
  which 
  Mr. 
  Chapman 
  has 
  identified 
  as 
  Flabellina 
  cordata, 
  

   Reuss, 
  a 
  representative 
  of 
  the 
  Nodosarininaa 
  most 
  commonly 
  present 
  

   in 
  the 
  Cenomanian. 
  Further 
  washing 
  of 
  the 
  marl 
  for 
  foraminifera 
  

   yielded 
  no 
  further 
  results. 
  

  

  Compared 
  with 
  the 
  previous 
  zone, 
  the 
  Grlauconitic 
  Marls 
  show 
  : 
  — 
  

   1. 
  A 
  diminution 
  in 
  the 
  size 
  and 
  quantity 
  of 
  the 
  glauconitic 
  

  

  grains. 
  

  

  . 
  2. 
  An 
  increase 
  in 
  the 
  calcareous 
  constituents. 
  

  

  3. 
  An 
  increase 
  in 
  the 
  amount 
  and 
  variety 
  of 
  the 
  contained 
  

   detrital 
  minerals, 
  accompanied 
  by 
  a 
  diminution 
  in 
  their 
  size. 
  

  

  4. 
  An 
  abundance 
  of 
  tourmaline, 
  particularly 
  in 
  the 
  crystal 
  form. 
  

   Especially 
  characteristic 
  of 
  these 
  marls 
  is 
  : 
  — 
  

  

  5. 
  The 
  abundance 
  and 
  variety 
  in 
  form 
  of 
  iron 
  pyrites. 
  

   "While 
  we 
  may 
  further 
  note 
  : 
  — 
  

  

  6. 
  The 
  presence 
  of 
  kyanite 
  and 
  garnet. 
  

  

  Grey 
  Marls 
  or 
  Yellow 
  Sandstone. 
  

   Woodburn 
  Glen. 
  (No. 
  4 
  a 
  in 
  Table 
  II.) 
  

  

  The 
  weight 
  of 
  material 
  employed 
  in 
  the 
  analysis 
  was 
  83*74 
  

   grammes. 
  After 
  solution 
  in 
  acid 
  the 
  insoluble 
  residue 
  yielded 
  : 
  — 
  

  

  ni 
  „ 
  ofioo 
  fCaCo 
  3 
  45-22% 
  

  

  Cla 
  ? 
  36-88grs. 
  or 
  | 
  Cky 
  * 
  ^.^ 
  

  

  Heavy 
  residue 
  ... 
  8'99 
  „ 
  = 
  Heavy 
  residue 
  10-73% 
  

  

  45-87 
  99-99 
  

  

  The 
  main 
  residue 
  consists 
  chiefly 
  of 
  finely-divided 
  clay 
  and 
  

   minute 
  quartz-grains. 
  

  

  