﻿^"°1* 
  53^ 
  PALEOZOIC 
  AGE 
  IN 
  THE 
  VARANSER 
  FIOED. 
  145 
  

  

  South 
  Africa 
  by 
  Dr. 
  Sutherland, 
  and 
  in 
  South 
  America, 
  and 
  though 
  

   their 
  exact 
  age 
  has 
  generally 
  been 
  in 
  doubt, 
  in 
  consequence 
  of 
  

   their 
  poverty 
  in 
  fossils, 
  many 
  of 
  them 
  have 
  been 
  assigned 
  to 
  a 
  

   late 
  Carboniferous 
  period 
  with 
  considerable 
  certainty. 
  Others 
  are 
  

   described 
  as 
  being 
  of 
  Permo-Carboniferous 
  age, 
  an 
  expression 
  which, 
  

   so 
  far 
  as 
  Western 
  Europe 
  is 
  concerned, 
  is 
  extremely 
  indefinite 
  ; 
  

   while 
  in 
  yet 
  a 
  few 
  cases 
  their 
  unconformable 
  relations 
  to 
  strata 
  

   bearing 
  Carboniferous 
  fossils 
  suggest 
  an 
  early 
  Mesozoic 
  age. 
  1 
  But 
  

   the 
  fact 
  that 
  several 
  of 
  the 
  glacially-formed 
  rocks 
  in 
  these 
  tropical 
  

   and 
  subtropical 
  regions 
  belong 
  to 
  approximately 
  the 
  same 
  date 
  

   seems 
  extremely 
  suggestive 
  of 
  a 
  temporary 
  but 
  general 
  change 
  

   of 
  climate 
  towards 
  the 
  close 
  of 
  the 
  Carboniferous 
  epoch, 
  as 
  sup- 
  

   posed 
  by 
  Feistmantel. 
  2 
  It 
  will 
  be 
  noted, 
  however, 
  that 
  the 
  only 
  

   example 
  hitherto 
  recorded 
  from 
  Northern 
  Europe 
  or 
  Asia 
  belongs, 
  

   if 
  Dr. 
  Eeusch's 
  correlation 
  proves 
  to 
  be 
  correct, 
  to 
  a 
  vastly 
  earlier 
  

   period. 
  

  

  The 
  section 
  which 
  I 
  have 
  described 
  lies 
  in 
  latitude 
  70° 
  8', 
  and 
  its 
  

   situation 
  so 
  far 
  north 
  may 
  be 
  taken 
  into 
  consideration 
  in 
  attempting 
  

   to 
  account 
  for 
  the 
  glacial 
  episode. 
  At 
  the 
  same 
  time 
  geographical 
  

   situation 
  does 
  not 
  explain 
  all 
  the 
  evidences 
  of 
  past 
  climates 
  that 
  we 
  

   possess, 
  for 
  not 
  only 
  do 
  the 
  Australian, 
  Indian, 
  and 
  African 
  glacial 
  

   deposits 
  lie 
  in 
  what 
  are 
  now 
  tropical 
  and 
  subtropical 
  regions, 
  but 
  

   rich 
  fossil 
  floras 
  and 
  faunas 
  have 
  been 
  obtained 
  in 
  younger 
  forma- 
  

   tions 
  far 
  north 
  of 
  the 
  Yaranger 
  Eiord. 
  Kor 
  can 
  the 
  phenomena 
  be 
  

   explained 
  by 
  supposing 
  the 
  existence 
  of 
  snow-covered 
  mountain- 
  

   ranges, 
  for 
  glaciers, 
  however 
  large 
  they 
  might 
  be, 
  would 
  not 
  reach 
  

   the 
  sea-level 
  and 
  distribute 
  boulders 
  in 
  marine 
  formations 
  in 
  or 
  

   near 
  the 
  tropics. 
  The 
  Gaisa 
  Beds, 
  so 
  far 
  as 
  I 
  saw 
  them, 
  do 
  not 
  

   suggest 
  the 
  immediate 
  neighbourhood 
  of 
  a 
  mountain-region, 
  for 
  such 
  

   conglomerates 
  as 
  they 
  contain 
  are 
  neither 
  coarse 
  nor 
  plentiful. 
  The 
  

   facts 
  tend 
  rather 
  to 
  indicate 
  a 
  temporary 
  deterioration 
  of 
  climate 
  

   both 
  in 
  this 
  and 
  the 
  other 
  instances 
  recorded, 
  but 
  how 
  far 
  the 
  Gaisa 
  

   episode 
  was 
  universal 
  (so 
  far 
  as 
  the 
  northern 
  part 
  of 
  the 
  globe 
  

   is 
  concerned) 
  it 
  must 
  be 
  left 
  to 
  future 
  investigations 
  to 
  determine. 
  

  

  Postscript. 
  

  

  [In 
  consequence 
  of 
  the 
  importance 
  of 
  the 
  point 
  raised 
  in 
  the 
  

   discussion 
  by 
  Sir 
  Archibald 
  Geikie, 
  thin 
  sections 
  of 
  the 
  boulder- 
  

   rock 
  and 
  underlying 
  quartzite 
  have 
  been 
  cut, 
  for 
  the 
  purpose 
  of 
  

   ascertaining 
  the 
  cause 
  of 
  their 
  hardness. 
  The 
  sections 
  show 
  that 
  

   the 
  grains 
  of 
  sand 
  which 
  form 
  a 
  large 
  proportion 
  of 
  the 
  matrix 
  of 
  

   the 
  boulder-rock, 
  as 
  well 
  as 
  those 
  composing 
  the 
  quartzite, 
  have 
  been 
  

   enlarged 
  by 
  the 
  deposition 
  of 
  secondary 
  silica 
  in 
  optical 
  continuity 
  

   with 
  the 
  original 
  grains. 
  The 
  induration 
  of 
  the 
  two 
  rocks 
  was 
  

   therefore 
  due 
  to 
  the 
  same 
  cause, 
  and 
  presumably 
  took 
  place 
  at 
  the 
  

  

  1 
  Thus 
  the 
  Dwyka 
  Conglomerate 
  and 
  associated 
  Karoo 
  Beds 
  of 
  South 
  Africa, 
  

   as 
  I 
  am 
  informed 
  by 
  Mr. 
  Gibson, 
  rest 
  quite 
  unconformably 
  upon 
  the 
  Zwarte- 
  

   bergen 
  Quartzite, 
  in 
  which 
  Mr. 
  Sawyer 
  has 
  obtained 
  Carboniferous 
  fossils, 
  

   Trans. 
  Fed. 
  Inst. 
  Min. 
  Eng. 
  vol. 
  ix. 
  p. 
  365. 
  

  

  2 
  Mem. 
  Geol. 
  Surv. 
  N.S.W. 
  (1890), 
  Pal., 
  No. 
  3, 
  p. 
  181. 
  

  

  