﻿Diastropfoism 
  in 
  Atlantic- 
  Arctic 
  Region. 
  17 
  

  

  some 
  of 
  the 
  chief 
  characteristics 
  of 
  the 
  northern 
  part 
  of 
  

   the 
  Appalachian 
  geosyncline. 
  If 
  we 
  assnme 
  a 
  curving 
  

   for 
  the 
  geosyncline 
  to 
  the 
  south 
  of 
  Eria 
  similar 
  to 
  that 
  

   of 
  the 
  northern 
  one 
  crossing 
  from 
  Europe 
  to 
  Arctic 
  

   America, 
  we 
  find 
  curving 
  troughs 
  around 
  the 
  greater 
  

   portion 
  of 
  this 
  old 
  land. 
  

  

  On 
  a 
  preceding 
  page 
  I 
  have 
  shown 
  in 
  tabular 
  form 
  the 
  

   more 
  important 
  orogenic 
  movements 
  occurring 
  in 
  pre- 
  

   Carboniferous 
  Paleozoic 
  time 
  in 
  this 
  Appalachian-north- 
  

   west 
  European-Arctic 
  geosynclinal 
  belt, 
  the 
  more 
  gentle 
  

   warpings 
  that 
  have 
  caused 
  no 
  unconformity 
  not 
  being 
  

   taken 
  into 
  consideration. 
  

  

  The 
  occurrence 
  of 
  a 
  period 
  of 
  folding 
  in 
  northern 
  

   Greenland 
  at 
  a 
  somewhat 
  later 
  time 
  than 
  that 
  of 
  the 
  

   Caledonian 
  deformation 
  of 
  Europe 
  seems 
  strongly 
  to 
  

   support 
  the 
  supposition 
  that 
  the 
  late 
  Devonian 
  move- 
  

   ments 
  in 
  the 
  northern 
  part 
  of 
  the 
  Appalachian 
  geosyn- 
  

   cline 
  may 
  well 
  be 
  looked 
  upon 
  as 
  a 
  delayed 
  Caledonian 
  

   deformation. 
  With 
  the 
  older 
  and 
  very 
  marked 
  diastro- 
  

   phic 
  movement 
  in 
  the 
  Appalachian 
  field, 
  the 
  late 
  Ordo- 
  

   vician 
  "Taconic" 
  disturbance, 
  there 
  certainly 
  took 
  place 
  

   great 
  contemporary 
  warpings 
  in 
  Europe. 
  Here, 
  how- 
  

   ever, 
  we 
  have 
  still 
  older 
  deformations 
  of 
  Middle 
  Ordo- 
  

   vician 
  time 
  that 
  appear 
  to 
  be 
  of 
  wide 
  occurrence. 
  This 
  

   would 
  mean, 
  then, 
  that 
  these 
  pre-Silurian 
  movements 
  of 
  

   Paleozoic 
  time 
  also 
  began 
  at 
  a 
  somewhat 
  earlier 
  date 
  on 
  

   the 
  European 
  side 
  than 
  on 
  the 
  American. 
  Furthermore, 
  

   the 
  fact 
  that 
  volcanic 
  activity, 
  partly 
  on 
  a 
  very 
  large 
  

   scale, 
  has 
  occurred 
  at 
  least 
  twice 
  in 
  western 
  Norway 
  dur- 
  

   ing 
  the 
  Ordovician, 
  and 
  in 
  the 
  British 
  Isles 
  at 
  various 
  

   places 
  practically 
  throughout 
  the 
  same 
  period, 
  strongly 
  

   indicates 
  that 
  the 
  British-Norwegian 
  part 
  of 
  the 
  geosyn- 
  

   cline 
  was 
  the 
  central, 
  originating 
  region 
  of 
  the 
  old 
  

   Paleozoic 
  crust 
  movements. 
  These 
  movements 
  spread 
  

   gradually 
  to 
  the 
  southwest 
  and 
  as 
  well 
  to 
  the 
  north, 
  

   finally 
  vanishing 
  in 
  the 
  extreme 
  end 
  of 
  the 
  trough. 
  

   Other 
  deformative 
  features, 
  however, 
  such 
  as 
  the 
  appear- 
  

   ance 
  and 
  disappearance 
  of 
  the 
  separating 
  longitudinal 
  

   barriers, 
  seem 
  to 
  be 
  somewhat 
  parallel 
  phenomena. 
  

   - 
  In 
  this 
  connection, 
  it 
  is 
  a 
  fact 
  of 
  further 
  interest 
  that 
  

   the 
  pre-Carboniferous 
  deformations 
  on 
  the 
  American 
  

   side 
  were 
  especially 
  well 
  marked 
  in 
  the 
  region 
  nearest 
  

   Europe, 
  i. 
  e., 
  in 
  the 
  northeastern 
  part 
  of 
  the 
  Appalachian 
  

   geosyncline. 
  Moreover, 
  this 
  early 
  and 
  intense 
  diastro- 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  XL1X, 
  No. 
  289.— 
  January, 
  1920. 
  

  

  2 
  

  

  