﻿Diastrophism 
  in 
  Atlantic- 
  Arctic 
  Region. 
  

  

  mations. 
  In 
  the 
  western 
  part 
  of 
  the 
  Girvan 
  area, 
  in 
  the 
  

   Llandeilian 
  series, 
  there 
  are 
  locally 
  huge 
  masses 
  of 
  

   coarse 
  conglomerates 
  which 
  lie 
  unconformably 
  above 
  

   the 
  Arenig 
  rocks, 
  which 
  make 
  rip 
  the 
  material 
  in 
  the 
  

   boulders 
  ; 
  in 
  the 
  Trondhjem 
  district 
  of 
  Norway 
  there 
  is 
  

   a 
  "greenstone 
  conglomerate, 
  ' 
  ' 
  the 
  pebbles 
  of 
  which 
  con- 
  

   sist 
  of 
  Lower 
  Ordovician 
  volcanics 
  and 
  intrusives 
  that 
  

   are 
  younger 
  than 
  the 
  volcanic 
  series. 
  A 
  very 
  consider- 
  

   able 
  uplift 
  followed 
  by 
  extensive 
  erosion 
  must 
  therefore 
  

   have 
  taken 
  place 
  in 
  this 
  region. 
  This 
  deformation 
  might 
  

   be 
  called 
  the 
  Trondhjem 
  disturbance. 
  As 
  probable 
  con- 
  

   temporary 
  movements 
  the 
  writer 
  considers 
  the 
  folding 
  

   of 
  the 
  Eaipas 
  series 
  of 
  western 
  Finmarken, 
  and 
  the 
  frac- 
  

   tures 
  leading 
  to 
  the 
  Varanger 
  fault 
  in 
  the 
  eastern 
  part 
  

   of 
  that 
  district. 
  

  

  There 
  was 
  also 
  considerable 
  volcanic 
  activity 
  during 
  

   youngest 
  Ordovician 
  time 
  in 
  the 
  same 
  geosyncline, 
  as 
  is 
  

   seen 
  in 
  different 
  parts 
  of 
  Britain 
  and 
  in 
  the 
  Stavanger- 
  

   Trondhjem 
  belt 
  of 
  southern 
  Norway. 
  Furthermore, 
  

   considerable 
  warping 
  took 
  place, 
  causing 
  the 
  emergence 
  

   of 
  much 
  land, 
  especially 
  in 
  the 
  British 
  Isles. 
  In 
  

   southern 
  Scandinavia, 
  strata 
  of 
  Upper 
  Ordovician 
  age 
  

   have 
  a 
  very 
  wide 
  distribution, 
  and 
  these 
  are 
  very 
  often 
  

   of 
  a 
  coarse 
  character, 
  with 
  conglomerates, 
  changing 
  

   much 
  from 
  place 
  to 
  place. 
  In 
  the 
  central 
  part 
  of 
  the 
  

   Kristiania 
  region, 
  the 
  sequence 
  demonstrates 
  temporary 
  

   and 
  local 
  emergence, 
  and 
  in 
  the 
  Trondhjem 
  region 
  there 
  

   are 
  very 
  thick 
  and 
  often 
  coarse 
  conglomerates. 
  The 
  

   barrier 
  of 
  the 
  preceding 
  time 
  is 
  no 
  longer 
  in 
  existence, 
  

   but 
  in 
  its 
  place 
  there 
  are 
  shallow 
  water-ways, 
  perhaps 
  

   rather 
  narrow, 
  yet 
  sufficient 
  for 
  a 
  free 
  communciation 
  

   between 
  the 
  previously 
  separated 
  ocean 
  basins. 
  

  

  Silurian 
  Time 
  (see 
  figs. 
  5 
  and 
  6). 
  — 
  As 
  in 
  the 
  Appala- 
  

   chian 
  geosyncline, 
  so 
  on 
  the 
  European 
  side 
  there 
  are 
  

   considerable 
  areas 
  emerged 
  in 
  Lower 
  Silurian 
  time, 
  and 
  

   especially 
  in 
  England 
  ; 
  while 
  further 
  to 
  the 
  northeast 
  

   the 
  Baltic 
  region 
  seems 
  to 
  have 
  been 
  dry, 
  although 
  the 
  

   land 
  was 
  very 
  low. 
  In 
  the 
  more 
  central 
  part 
  of 
  the 
  

   Scandinavian 
  sea 
  the 
  sediments 
  often 
  have 
  a 
  rather 
  

   coarse 
  character. 
  

  

  Middle 
  Silurian 
  time, 
  as 
  is 
  well 
  known, 
  is 
  one 
  of 
  very 
  

   large 
  marine 
  transgression, 
  and 
  over 
  large 
  areas 
  of 
  the 
  

   northern 
  lands, 
  especially 
  in 
  North 
  America. 
  Yet 
  if 
  we 
  

   consider 
  the 
  whole 
  northern 
  area, 
  we 
  may 
  also 
  see, 
  in 
  

   local 
  districts, 
  a 
  widening 
  of 
  the 
  land. 
  In 
  fact, 
  the 
  Cale- 
  

  

  