﻿GEOLOGICAL 
  CLIMATES 
  SCOTT 
  287 
  

  

  It 
  may 
  not 
  seem 
  legitimate 
  to 
  assume 
  that 
  the 
  existing 
  wind 
  system 
  

   extended 
  so 
  far 
  back 
  into 
  the 
  distant 
  past; 
  but 
  as 
  a 
  matter 
  of 
  fact 
  

   this 
  system, 
  aside 
  from 
  local 
  currents, 
  is 
  in 
  Davis's 
  phrase 
  "plane- 
  

   tary," 
  and 
  is 
  determined 
  by 
  the 
  earth's 
  relations 
  as 
  a 
  planet. 
  So 
  long 
  

   as 
  the 
  earth 
  rotates 
  on 
  its 
  axis 
  and 
  revolves 
  about 
  the 
  sun 
  ; 
  so 
  long 
  

   as 
  its 
  axis 
  remains 
  oblique 
  to 
  the 
  plane 
  of 
  its 
  orbit, 
  producing 
  differ- 
  

   ences 
  of 
  temperature 
  in 
  different 
  regions, 
  so 
  long 
  must 
  the 
  general 
  

   system 
  of 
  winds 
  remain 
  what 
  it 
  is 
  now 
  and 
  what 
  we 
  have 
  every 
  

   reason 
  to 
  believe 
  it 
  has 
  always 
  been 
  from 
  the 
  beginning 
  of 
  land 
  and 
  

   sea. 
  Raising 
  and 
  lowering 
  the 
  atmospheric 
  temperature 
  will 
  un- 
  

   doubtedly 
  shift 
  the 
  position 
  of 
  the 
  wind 
  belts, 
  but 
  will 
  not 
  affect 
  

   them 
  otherwise. 
  

  

  We 
  have 
  direct 
  proof 
  that 
  in 
  the 
  Pleistocene, 
  at 
  least, 
  the 
  system 
  

   of 
  winds 
  was 
  substantially 
  the 
  same 
  as 
  now. 
  Everyone 
  is 
  familiar 
  

   with 
  the 
  fact 
  that 
  the 
  western 
  side 
  of 
  Europe 
  has 
  a 
  much 
  milder 
  

   climate 
  than 
  the 
  Atlantic 
  coast 
  of 
  North 
  America, 
  with 
  no 
  such 
  

   extremes 
  of 
  temperature. 
  Great 
  Britain 
  and 
  Labrador, 
  Norway 
  and 
  

   Greenland, 
  New 
  York 
  and 
  Naples 
  have 
  much 
  the 
  same 
  latitude. 
  The 
  

   difference 
  in 
  climate, 
  which 
  amounts 
  to 
  10° 
  of 
  latitude, 
  is 
  due 
  to 
  the 
  

   westerly 
  Avinds, 
  which 
  reach 
  Europe 
  from 
  the 
  sea, 
  eastern 
  North 
  

   America 
  from 
  the 
  land. 
  The 
  same 
  climatic 
  difference, 
  and 
  for 
  the 
  

   same 
  reason, 
  obtains 
  between 
  the 
  Atlantic 
  and 
  Pacific 
  coasts 
  of 
  North 
  

   America 
  and 
  between 
  the 
  American 
  and 
  Asiatic 
  shores 
  of 
  the 
  Pacific. 
  

   During 
  the 
  maximum 
  glaciation 
  in 
  the 
  Pleistocene 
  the 
  extension 
  of 
  

   the 
  northern 
  ice 
  caps 
  was 
  to 
  latitude 
  50° 
  in 
  Europe 
  and 
  40° 
  in 
  eastern 
  

   North 
  America, 
  just 
  such 
  a 
  difference 
  as 
  we 
  find 
  to-day. 
  

  

  The 
  studies 
  of 
  Professor 
  Huntington 
  have 
  satisfied 
  most 
  geog- 
  

   raphers 
  of 
  the 
  reality 
  of 
  the 
  desiccation, 
  which 
  has 
  been 
  in 
  progress 
  

   for 
  the 
  last 
  2,000 
  years, 
  from 
  central 
  and 
  western 
  Asia 
  to 
  California. 
  

   The 
  desiccation 
  has 
  not 
  been 
  uniformly 
  progressive, 
  but 
  subject 
  to 
  

   wide 
  fluctuations, 
  though 
  the 
  algebraic 
  sum 
  of 
  the 
  fluctuations 
  is 
  

   greatly 
  increased 
  dryness. 
  Whether 
  this 
  increasing 
  aridity 
  can 
  be 
  

   correlated 
  with 
  rising 
  temperature 
  is 
  not 
  yet 
  known, 
  but 
  it 
  must 
  be 
  

   said 
  that 
  we 
  know 
  no 
  cause 
  of 
  desiccation 
  except 
  greater 
  heat. 
  

  

  I 
  should, 
  perhaps, 
  apologize 
  to 
  the 
  members 
  of 
  the 
  society 
  for 
  

   selecting 
  as 
  the 
  topic 
  of 
  this 
  address 
  so 
  hackneyed 
  a 
  problem 
  as 
  that 
  

   of 
  geological 
  climates, 
  in 
  which 
  it 
  is 
  hardly 
  possible 
  to 
  suggest 
  any- 
  

   thing 
  that 
  has 
  not 
  been 
  suggested 
  many 
  times 
  before. 
  It 
  is, 
  indeed, 
  a 
  

   threshing 
  over 
  of 
  old 
  straw. 
  Yet 
  there 
  has 
  been 
  so 
  emphatic 
  a 
  

   revival 
  of 
  interest 
  in 
  the 
  problem 
  of 
  late 
  years 
  that 
  I 
  thought 
  it 
  

   might 
  serve 
  a 
  useful 
  purpose 
  to 
  offer 
  a 
  brief 
  consideration, 
  in 
  classi- 
  

   fied 
  form, 
  of 
  the 
  many 
  factors 
  of 
  climatic 
  change 
  which 
  have 
  been 
  

   brought 
  forward 
  in 
  many 
  lands 
  and 
  by 
  many 
  writers. 
  

  

  