﻿496 
  T. 
  BELT 
  ON 
  THE 
  STEPPES 
  OE 
  SIBERIA. 
  

  

  Let 
  us 
  see 
  if 
  such 
  a 
  barrier 
  would 
  account 
  for 
  the 
  formation 
  of 
  

   the 
  steppes. 
  Siberia 
  is 
  a 
  great 
  continental 
  basin, 
  surrounded 
  on 
  

   three 
  sides 
  by 
  the 
  mountain-chains 
  of 
  the 
  Oural, 
  the 
  Altai, 
  and 
  the 
  

   Stannovoi 
  ; 
  and 
  the 
  only 
  outlets 
  of 
  its 
  drainage 
  are 
  to 
  the 
  north. 
  If 
  

   an 
  overflow 
  of 
  ice 
  took 
  place 
  from 
  the 
  north, 
  the 
  waters 
  of 
  all 
  the 
  

   rivers 
  would 
  be 
  pounded 
  back. 
  As 
  the 
  ice 
  advanced 
  southwards 
  

   it 
  would 
  grind 
  against 
  the 
  bed-rocks, 
  and 
  the 
  water 
  issuing 
  from 
  

   below 
  it 
  would 
  wash 
  out 
  sand 
  and 
  silt. 
  Where 
  ranges 
  rose 
  above 
  

   it, 
  boulders 
  would 
  be 
  carried 
  southward 
  ; 
  and 
  those 
  noticed 
  by 
  

   Erman 
  at 
  Samarova 
  were 
  probably 
  brought 
  from 
  the 
  northern 
  end 
  

   of 
  the 
  Ourals. 
  At 
  its 
  culmination 
  I 
  do 
  not 
  think 
  it 
  reached 
  

   much 
  further 
  south 
  than 
  Pavlodav, 
  as 
  the 
  steppe-sands 
  thin 
  out 
  

   rapidly, 
  and 
  there 
  is 
  no 
  sign 
  of 
  glaciation 
  on 
  the 
  surface 
  of 
  the.ex- 
  

   posed 
  rocks 
  fifty 
  miles 
  to 
  the 
  south. 
  The 
  edge 
  of 
  the 
  ice 
  would 
  

   mark 
  the 
  commencement 
  of 
  a 
  great 
  lake 
  into 
  which 
  would 
  run 
  all 
  

   the 
  streams 
  from 
  the 
  south 
  and 
  all 
  the 
  water 
  from 
  the 
  melting 
  ice. 
  

   At 
  its 
  greatest 
  elevation 
  I 
  believe 
  the 
  overflow 
  of 
  this 
  lake 
  must 
  

   have 
  run 
  through 
  the 
  depression 
  between 
  the 
  southern 
  termination 
  

   of 
  the 
  Ourals 
  and 
  the 
  western 
  end 
  of 
  the 
  Altai 
  to 
  the 
  Aral 
  and 
  

   Caspian 
  Seas. 
  

  

  During 
  the 
  slow 
  retreat 
  of 
  the 
  ice 
  the 
  water 
  would 
  follow 
  its 
  

   receding 
  margin 
  ; 
  and 
  every 
  portion 
  of 
  the 
  growing 
  steppe 
  would 
  at 
  

   one 
  time 
  or 
  the 
  other 
  form 
  part 
  of 
  the 
  shore 
  of 
  the 
  great 
  lake. 
  

  

  Around 
  this 
  shore, 
  and 
  on 
  the 
  banks 
  of 
  the 
  rivers 
  flowing 
  into 
  the 
  

   lake, 
  I 
  believe 
  the 
  great 
  mammalia 
  lived 
  ; 
  and 
  as 
  the 
  water 
  moved 
  

   northward 
  they 
  followed 
  its 
  margin 
  ; 
  and 
  their 
  remains 
  are 
  thus 
  

   found 
  dispersed 
  over 
  the 
  whole 
  area 
  of 
  the 
  steppes. 
  Their 
  frozen 
  

   . 
  carcasses 
  found 
  along 
  with 
  sea-shells 
  in 
  the 
  far 
  north 
  prove 
  that 
  

   they 
  lived 
  up 
  to 
  the 
  close 
  of 
  the 
  Glacial 
  period, 
  whilst 
  their 
  bones, 
  

   in 
  caves 
  far 
  to 
  the 
  south 
  in 
  the 
  Altai, 
  probably 
  mark 
  their 
  range 
  at 
  

   the 
  time 
  of 
  its 
  greatest 
  intensity. 
  

  

  I 
  have 
  shown 
  that 
  the 
  ranges 
  to 
  the 
  north 
  of 
  Pavlodav 
  exhibit 
  no 
  

   signs 
  of 
  ever 
  having 
  supported 
  glaciers. 
  If 
  we 
  glance 
  at 
  a 
  map 
  of 
  

   Asia 
  we 
  shall 
  see 
  that 
  currents 
  of 
  air 
  coming 
  from 
  the 
  south 
  would, 
  

   before 
  they 
  reached 
  Siberia, 
  have 
  to 
  cross 
  the 
  high 
  mountains 
  of 
  

   India 
  and 
  Central 
  Asia, 
  where 
  they 
  could 
  not 
  fail 
  to 
  part 
  with 
  their 
  

   moisture 
  ; 
  so 
  that 
  the 
  precipitation 
  in 
  Siberia 
  was 
  probably 
  not 
  

   greater, 
  but 
  less, 
  in 
  the 
  Glacial 
  period 
  than 
  it 
  is 
  now. 
  Whence 
  then 
  

   came 
  the 
  ice 
  that 
  blocked 
  up 
  the 
  drainage 
  of 
  Siberia? 
  I 
  believe 
  it 
  

   was 
  an 
  overflow 
  from 
  the 
  polar 
  basin, 
  which 
  was 
  filled 
  with 
  ice 
  that 
  

   poured 
  into 
  it 
  from 
  the 
  northern 
  extremities 
  of 
  America, 
  Greenland, 
  

   and 
  Europe, 
  and 
  which 
  was 
  further 
  heaped 
  up 
  towards 
  the 
  pole 
  by 
  

   precipitation 
  from 
  moisture-bearing 
  currents 
  of 
  air 
  that 
  travelled 
  

   far 
  north, 
  through 
  Behring's 
  Straits 
  and 
  past 
  Spitzbergen. 
  

  

  3. 
  Application 
  oe 
  the 
  Theory 
  to 
  other 
  parts 
  oe 
  the 
  Earth's 
  

   Surface. 
  

  

  Eight 
  years 
  ago, 
  in 
  a 
  paper 
  on 
  the 
  Glacial 
  period 
  in 
  North 
  America, 
  

   I 
  suggested 
  that 
  certain 
  phenomena 
  thought 
  to 
  prove 
  that 
  there 
  had 
  

  

  