﻿20 
  0. 
  Holtedahl 
  — 
  Paleo 
  geography 
  and 
  

  

  ica 
  and 
  northwestern 
  Europe, 
  the 
  likeness 
  is 
  exceedingly- 
  

   great, 
  except 
  that 
  the 
  arrangement 
  of 
  the 
  different 
  ele- 
  

   ments 
  is 
  reversed. 
  First, 
  we 
  have 
  the 
  two 
  well-known 
  

   shields, 
  which 
  Sness 
  pointed 
  ont 
  as 
  decided 
  geological 
  ele- 
  

   ments. 
  Between 
  the 
  "positive" 
  Canadian 
  mass 
  and 
  the 
  

   Appalachian 
  geosyncline 
  comes 
  a 
  "neutral" 
  area, 
  belong- 
  

   ing 
  to 
  the 
  rigid 
  part 
  of 
  the 
  continent 
  but 
  differing 
  from 
  

   the 
  shield 
  in 
  having 
  a 
  cover 
  of 
  sedimentary 
  rocks 
  that 
  tells 
  

   of 
  an 
  average 
  low 
  level 
  in 
  regard 
  to 
  the 
  sea. 
  A 
  similar 
  

   "neutral" 
  area 
  exists 
  on 
  the 
  European 
  side, 
  where 
  

   Sweden 
  and 
  the 
  southeastern 
  part 
  of 
  Norway 
  belong 
  to 
  

   it. 
  It 
  must 
  be 
  borne 
  in 
  mind 
  that, 
  even 
  though 
  folding 
  

   occurs 
  far 
  to 
  the 
  east 
  in 
  the 
  Scandinavian 
  Peninsula, 
  

   and 
  in 
  the 
  greater 
  part 
  of 
  the 
  Kristiania 
  region, 
  the 
  real 
  

   zone 
  of 
  deformation 
  is 
  limited 
  to 
  a 
  narrower 
  and 
  more 
  

   western 
  belt. 
  The 
  folding 
  to 
  the 
  east 
  has 
  not 
  affected 
  

   the 
  basal 
  pre-Cambrian 
  floor; 
  the 
  folding 
  of 
  the 
  sedi- 
  

   mentary 
  beds 
  above 
  the 
  older 
  floor 
  is 
  therefore 
  of 
  a 
  

   secondary 
  character, 
  caused 
  indirectly, 
  so 
  to 
  speak, 
  by 
  

   the 
  deformative 
  processes 
  (especially 
  thrusting) 
  that 
  

   took 
  place 
  in 
  the 
  more 
  central 
  (northwestern) 
  zone. 
  

   This 
  distinction 
  between 
  zones 
  of 
  only 
  indirect 
  deforma- 
  

   tion, 
  where 
  the 
  basal 
  rock 
  floor 
  has 
  been 
  left 
  undef 
  ormed, 
  

   and 
  the 
  true 
  zone 
  of 
  deep-ranging 
  deformation, 
  is 
  cer- 
  

   tainly 
  a 
  point 
  of 
  great 
  importance, 
  and 
  one 
  often 
  neg- 
  

   lected 
  in 
  the 
  discussion 
  of 
  the 
  nature 
  of 
  the 
  deformations 
  

   of 
  folding 
  ranges. 
  In 
  the 
  Scandinavian 
  Peninsula, 
  with 
  

   its 
  highly 
  elevated, 
  and 
  in 
  large 
  areas 
  uncovered, 
  pre- 
  

   Cambrian 
  floor, 
  there 
  is 
  a 
  singular 
  opportunity 
  of 
  study- 
  

   ing 
  the 
  deformation 
  of 
  the 
  more 
  compact 
  part 
  of 
  the 
  

   crust. 
  

  

  Crossing 
  over, 
  then, 
  to 
  the 
  next 
  element 
  which 
  has 
  

   already 
  been 
  considered, 
  the 
  geosyncline 
  itself, 
  in 
  

   America 
  we 
  reach 
  the 
  ancient 
  land 
  of 
  Appalachia 
  (and 
  

   Acadia), 
  a 
  region 
  of 
  uncertain 
  width. 
  A 
  dominant 
  

   character 
  of 
  this 
  land 
  (or 
  lands) 
  bordering 
  the 
  geosyn- 
  

   cline 
  to 
  the 
  east 
  must 
  be 
  the 
  power 
  of 
  rejuvenation, 
  since 
  

   it 
  is 
  thought 
  to 
  have 
  been 
  the 
  source 
  of 
  the 
  huge 
  masses 
  

   of 
  sediments 
  deposited 
  through 
  a 
  number 
  of 
  geological 
  

   periods. 
  This, 
  as 
  we 
  have 
  indicated, 
  was 
  also 
  a 
  charac- 
  

   teristic 
  feature 
  of 
  the 
  Paleozoic 
  land 
  west 
  of 
  the 
  north- 
  

   west 
  European-Arctic 
  geosyncline, 
  a 
  land 
  that 
  is 
  the 
  

   natural 
  parallel 
  to 
  that 
  of 
  Appalachia. 
  The 
  rising 
  of 
  

   the 
  northern 
  land 
  became 
  especially 
  effective 
  in 
  the 
  later 
  

  

  