﻿IS 
  THE 
  EARTH 
  GROWING 
  OLD? 
  POMPECKJ 
  267 
  

  

  The 
  intensity 
  of 
  the 
  folding, 
  neglecting 
  the 
  wholly 
  undetermined 
  

   relations 
  of 
  the 
  Archaic-Algonkian 
  times, 
  has 
  certainly 
  not 
  de- 
  

   creased; 
  it 
  has 
  rather 
  increased. 
  It 
  is 
  difficult 
  to 
  reconstruct 
  the 
  

   mountains 
  of 
  the 
  remote 
  past 
  out 
  of 
  the 
  worn-down 
  remains 
  and 
  

   then 
  to 
  estimate 
  the 
  magnitudes 
  of 
  the 
  corresponding 
  foldings. 
  

   We 
  do 
  indeed 
  have 
  many 
  pictures 
  of 
  highly 
  complicated 
  foldings, 
  in 
  

   the 
  broader 
  significance 
  of 
  the 
  term, 
  in 
  the 
  Caledonian 
  of 
  Scotland 
  

   and 
  Scandinavia 
  and 
  in 
  the 
  Variscian 
  Appalachians 
  of 
  North 
  Amer- 
  

   ica, 
  but 
  it 
  seems 
  to 
  me 
  idle 
  to 
  look 
  in 
  our 
  Variscian 
  Rhenish 
  moun- 
  

   tains 
  for 
  such 
  foldings, 
  for 
  example, 
  as 
  the 
  Simplon 
  Tunnel 
  has 
  

   revealed 
  in 
  the 
  structure 
  of 
  the 
  Alps. 
  The 
  Variscian 
  foldings 
  in 
  

   middle 
  Europe 
  were 
  manifested 
  upon 
  a 
  far 
  broader 
  basis 
  than 
  in 
  

   our 
  Alps. 
  I 
  gather 
  from 
  them 
  the 
  impression 
  that 
  on 
  the 
  whole 
  they 
  

   are 
  less 
  comj^licated 
  than 
  the 
  more 
  recent 
  Alpidian. 
  

  

  The 
  Alpidian 
  folding 
  occurred 
  over 
  world-wide 
  areas. 
  Its 
  extent 
  

   was 
  certainly 
  not 
  less 
  than 
  the 
  Variscian; 
  it 
  is 
  known 
  to 
  be 
  greater 
  

   than 
  the 
  Caledonian 
  folding. 
  

  

  All 
  of 
  this 
  leads 
  me 
  to 
  the 
  conclusion 
  that 
  the 
  possibility 
  and 
  the 
  

   intensity 
  of 
  these 
  movements 
  of 
  the 
  earth's 
  crust 
  in 
  the 
  mobile 
  zone 
  

   or 
  in 
  zones 
  which 
  may 
  become 
  mobile 
  and 
  whence 
  mountains 
  may 
  be 
  

   born, 
  are 
  certainly 
  not 
  decreasing. 
  In 
  the 
  processes 
  of 
  folding 
  there 
  

   is 
  nothing 
  that 
  indicates 
  that 
  the 
  earth 
  is 
  becoming 
  senile. 
  

  

  During 
  the 
  geological 
  present 
  the 
  earth 
  is 
  again 
  in 
  a 
  relatively 
  

   quiet 
  period. 
  The 
  continental 
  blocks 
  stand 
  under 
  the 
  influence 
  of 
  a 
  

   geocratic 
  period 
  such 
  as 
  once 
  followed 
  the 
  Variscian 
  folding 
  in 
  Western 
  

   Europe 
  during 
  the 
  upper 
  Carboniferous, 
  the 
  Dyas, 
  and 
  the 
  Triassic. 
  

   Under 
  the 
  still 
  effective 
  influence 
  of 
  the 
  Alpidian 
  folding, 
  the 
  neigh- 
  

   boring 
  regions 
  are 
  subjected 
  to 
  such 
  climatic 
  factors 
  that 
  the 
  move- 
  

   ments 
  and 
  geological 
  action 
  of 
  the 
  hydrosphere 
  are 
  still 
  very 
  inten- 
  

   sive. 
  The 
  amount 
  of 
  these 
  actions 
  will 
  be 
  quite 
  difrerent 
  when 
  these 
  

   young 
  mountains 
  have 
  been 
  more 
  and 
  more 
  worn 
  down 
  ; 
  for 
  instance, 
  

   the 
  regional 
  climatic 
  differences 
  will 
  be 
  equalized 
  throughout 
  middle 
  

   Europe. 
  There 
  will 
  then 
  be 
  a 
  repetition 
  of 
  the 
  picture 
  which 
  pre- 
  

   vailed 
  at 
  first 
  in 
  the 
  quiescent 
  periods 
  of 
  the 
  Triassic 
  and 
  the 
  Jurassic. 
  

   However, 
  it 
  will 
  be 
  only 
  the 
  expression 
  of 
  a 
  temporary 
  mode, 
  not 
  a 
  

   senile 
  weakening 
  of 
  the 
  atmospheric 
  powers. 
  

  

  Since 
  not 
  confirmed 
  by 
  any 
  geological 
  evidence, 
  the 
  idea 
  has 
  been 
  

   long 
  given 
  up 
  of 
  a 
  steady 
  decrease 
  of 
  the 
  temperature 
  of 
  the 
  earth 
  

   from 
  early 
  times 
  until 
  the 
  present, 
  although 
  it 
  influenced 
  geological 
  

   thought 
  for 
  a 
  long 
  time. 
  The 
  demonstration 
  of 
  early 
  ice 
  ages 
  in 
  the 
  

   Dyas, 
  in 
  the 
  Devonian, 
  in 
  the 
  pre-Cambrian, 
  forces 
  us 
  to 
  discard 
  it 
  

   because 
  of 
  the 
  proof 
  by 
  Sartorious 
  von 
  Waltershausen, 
  now 
  three- 
  

   quarters 
  of 
  a 
  century 
  old, 
  that 
  a 
  rock 
  crust 
  at 
  the 
  earth's 
  surface 
  of 
  

   only 
  3 
  kilometers 
  thickness 
  practically 
  makes 
  the 
  temperature 
  of 
  the 
  

  

  