﻿OF 
  DIAMONDS 
  IN 
  SOUTH 
  AFRICA. 
  

  

  Ol 
  

  

  daloid 
  cover 
  the 
  surface 
  of 
  the 
  couutry, 
  in 
  places, 
  several 
  inches 
  deep. 
  

   Where 
  masses 
  of 
  shale 
  have 
  been 
  entangled 
  in 
  the 
  igneous 
  rock, 
  it 
  

   has 
  been 
  altered 
  into 
  honistone. 
  

  

  Diamonds 
  have 
  been 
  distributed 
  from 
  their 
  original 
  position 
  in 
  

   the 
  igneous 
  rock 
  by 
  three 
  distinct 
  agencies 
  — 
  water, 
  ice, 
  and 
  the 
  

   wind. 
  

  

  To 
  the 
  action 
  of 
  running 
  water 
  the 
  diamond-bearing 
  drifts 
  of 
  the 
  

   Vaal 
  river 
  are 
  referable. 
  They 
  are 
  of 
  two 
  dates. 
  The 
  older 
  one, 
  

  

  Pig. 
  1. 
  — 
  Plan 
  and 
  Section 
  of 
  Pipe 
  on 
  Fisher's 
  Farm, 
  Shietfontein. 
  

   (Scale, 
  10 
  chains 
  to 
  1 
  inch.) 
  

  

  Whd 
  

  

  a. 
  Plan. 
  b. 
  Vertical 
  section 
  in 
  line 
  c 
  d. 
  

  

  apparently 
  Postpliocene, 
  occurs 
  at 
  a 
  higher 
  level 
  than 
  the 
  other, 
  as 
  

   outliers 
  along 
  the 
  present 
  valley 
  (its 
  present 
  position) 
  indicate 
  that 
  

   the 
  Vaal 
  has 
  deepened 
  its 
  course 
  since 
  the 
  old 
  drift 
  was 
  deposited. 
  

  

  The 
  famous 
  Pniel 
  Kopje 
  was 
  of 
  this 
  age, 
  the 
  depth 
  of 
  sinking, 
  

   about 
  30 
  feet, 
  consisting 
  of 
  a 
  few 
  feet 
  of 
  fine 
  gravel, 
  composed 
  

   of 
  agates, 
  chalcedony, 
  amygdaloid, 
  dolerite, 
  &c, 
  with 
  some 
  gar- 
  

   nets, 
  ilmenite, 
  topaz, 
  quartz, 
  and 
  diamonds. 
  Below 
  this, 
  in 
  places, 
  

   was 
  a 
  hard 
  layer 
  of 
  conglomerate, 
  the 
  pebbles 
  cemented 
  with 
  lime. 
  

   The 
  remainder 
  of 
  the 
  drift 
  was 
  composed 
  of 
  large 
  boulders 
  of 
  igneous 
  

   rock, 
  exceedingly 
  tough 
  and 
  hard, 
  with 
  fine 
  drift 
  containing 
  diamonds 
  

   filling 
  the 
  interstices. 
  The 
  . 
  bottom 
  is 
  soft 
  igneous 
  rock, 
  probably 
  

   dolerite. 
  

  

  At 
  Gong 
  Gong 
  a 
  calcareous 
  conglomerate 
  occurs 
  high 
  above 
  

   the 
  recent 
  drift, 
  and 
  appears 
  to 
  belong 
  to 
  the 
  same 
  age 
  as 
  the 
  Pniel 
  

   drift. 
  Wherever 
  worked, 
  along 
  the 
  course 
  of 
  the 
  Vaal, 
  diamonds 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  117. 
  f 
  

  

  