﻿680 
  Geological 
  Society. 
  

  

  The 
  difference, 
  observable 
  in 
  the 
  artificially-worked 
  stones 
  from 
  

   defined 
  areas 
  on 
  both 
  sides 
  of 
  the 
  Zambesi, 
  is 
  shown 
  by 
  a 
  com- 
  

   parison 
  of 
  numerous 
  specimens 
  collected 
  by 
  the 
  author. 
  The 
  

   very 
  large 
  majority 
  of 
  flakes 
  and 
  flaked 
  stones 
  having 
  no 
  trace 
  of 
  

   design, 
  over 
  those 
  that 
  can 
  be 
  considered 
  as 
  implements, 
  however 
  

   rough, 
  suggests 
  that 
  the 
  manufacture 
  of 
  stone 
  tools 
  on 
  a 
  large 
  scale 
  

   was 
  here 
  carried 
  on 
  for 
  use 
  in 
  the 
  sand- 
  covered 
  country 
  on 
  both 
  

   sides 
  of 
  the 
  Zambesi, 
  where 
  there 
  is 
  no 
  stone 
  ; 
  and 
  the 
  difference, 
  

   in 
  the 
  proportion 
  of 
  sharp 
  unworn 
  specimens 
  to 
  those 
  apparently 
  

   waterworn, 
  seems 
  to 
  show 
  that 
  while 
  many 
  were 
  made 
  on 
  the 
  

   ground, 
  the 
  flakes 
  and 
  refuse 
  of 
  the 
  making 
  of 
  many 
  more 
  were 
  

   brought 
  down 
  from 
  the 
  tributary 
  valley 
  on 
  the 
  east. 
  

  

  The 
  author 
  considers 
  that 
  there 
  is 
  no 
  evidence 
  as 
  to 
  the 
  age 
  of 
  

   the 
  implements 
  found 
  near 
  the 
  Zambesi 
  ; 
  none 
  have 
  been 
  discovered 
  

   in 
  gravel 
  that 
  belongs 
  to 
  that 
  river, 
  and 
  the 
  presumption 
  appears 
  

   strong 
  that 
  they 
  were 
  made 
  from 
  quartzite 
  found 
  on 
  the 
  surface 
  

   since 
  the 
  Eatoka 
  Gorge 
  was 
  eroded. 
  

  

  2. 
  ' 
  A 
  Contribution 
  to 
  the 
  Petrography 
  of 
  the 
  New 
  Eed 
  Sand- 
  

   stone 
  in 
  the 
  West 
  of 
  England.' 
  By 
  Herbert 
  Henry 
  Thomas, 
  M.A., 
  

   E.Sc, 
  F.G.S. 
  

  

  The 
  paper 
  is 
  supplementary 
  to 
  that 
  which 
  dealt 
  with 
  the 
  

   mineralogical 
  composition 
  of 
  the 
  Pebble-Bed, 
  and 
  was 
  published 
  in 
  

   vol. 
  Iviii. 
  of 
  the 
  Quarterly 
  Journal 
  (1902) 
  p. 
  620. 
  The 
  results 
  

   obtained 
  are 
  based 
  on 
  the 
  microscopic 
  investigation 
  of 
  a 
  large 
  

   number 
  of 
  samples 
  taken 
  from 
  various 
  New 
  Eed 
  horizons 
  and 
  

   localities 
  in 
  Devon 
  and 
  Somerset. 
  

  

  The 
  author 
  gives 
  a 
  list 
  of 
  minerals 
  identified, 
  and 
  tables 
  showing 
  

   their 
  distribution. 
  In 
  the 
  description 
  of 
  certain 
  mineral 
  species, 
  it 
  

   is 
  suggested 
  that 
  anatase 
  occurs 
  both 
  as 
  detrital 
  crystals 
  and 
  as 
  

   crystalline 
  groups 
  formed 
  in 
  the 
  rocks 
  since 
  their 
  deposition. 
  The 
  

   forms 
  presented 
  by 
  grains 
  of 
  staurolite 
  as 
  well 
  as 
  certain 
  crystals 
  

   of 
  tourmaline 
  with 
  an 
  unusual 
  habit 
  are 
  described. 
  

  

  It 
  is 
  recognized 
  that 
  the 
  various 
  divisions 
  of 
  the 
  New 
  Eed 
  Sand- 
  

   stone, 
  namel)^ 
  the 
  Lower 
  Breccias 
  and 
  Sandstones, 
  the 
  Lower 
  Marls, 
  

   the 
  Pebble-Bed, 
  and 
  the 
  Upper 
  Marls 
  and 
  Sandstones, 
  although 
  

   linked 
  together 
  by 
  a 
  general 
  similarity 
  of 
  mineralogical 
  composition, 
  

   present 
  physical 
  and 
  mineralogical 
  differences 
  indicative 
  of 
  varia- 
  

   tions 
  in 
  the 
  source 
  of 
  supply 
  and 
  conditions 
  of 
  deposition. 
  

  

  The 
  rounding 
  of 
  the 
  grains 
  is 
  most 
  complete 
  (millet-seed) 
  in 
  the 
  

   sandstones 
  of 
  the 
  Lower 
  Breccias 
  and 
  Sandstones, 
  a 
  feature 
  con- 
  

   tinued, 
  but 
  in 
  a 
  less 
  striking 
  manner, 
  into 
  the 
  overlying 
  division. 
  

  

  With 
  regard 
  to 
  the 
  vertical 
  and 
  horizontal 
  distribution 
  of 
  minerals, 
  

   it 
  is 
  found 
  that 
  staurolite 
  is 
  abundant 
  in 
  the 
  Lower 
  Breccias 
  and 
  

   Sandstones 
  of 
  the 
  extreme 
  south 
  of 
  Devon, 
  but 
  less 
  plentiful 
  north- 
  

   wards 
  ; 
  that 
  garnet 
  is 
  present 
  in 
  all 
  the 
  New 
  Eed 
  rocks 
  of 
  North 
  

   Devon 
  and 
  Somerset, 
  but 
  in 
  South 
  and 
  Central 
  Devon 
  only 
  occurs 
  

   in 
  the 
  Lower 
  Marls 
  and 
  in 
  the 
  Upper 
  Marls 
  and 
  Sandstones. 
  

  

  