﻿IS 
  THE 
  EARTH 
  GROWING 
  OLD? 
  POMPEGKJ 
  269 
  

  

  compare 
  with 
  that 
  of 
  by-gone 
  times? 
  The 
  mimber 
  of 
  active 
  vol- 
  

   canoes 
  since 
  1800 
  has 
  been 
  231. 
  The 
  number 
  of 
  submarine 
  outbreaks 
  

   is 
  unknown. 
  The 
  vulcanism 
  of 
  to-day 
  was 
  exceeded 
  certainly 
  by 
  that 
  

   of 
  the 
  past 
  only 
  for 
  a 
  few 
  periods 
  of 
  equal 
  shortness. 
  The 
  area 
  of 
  

   900 
  square 
  kilometers 
  forming 
  the 
  surface 
  covered 
  with 
  lava 
  from 
  the 
  

   Skaptar 
  eruption 
  of 
  1783 
  on 
  Iceland, 
  the 
  recent 
  and 
  near-recent 
  lava 
  

   flows 
  building 
  up 
  the 
  Hawaiian 
  Islands 
  or 
  the 
  Aetna, 
  do 
  not 
  take 
  

   second 
  place 
  when 
  compared 
  with 
  the 
  many 
  eruptions 
  of 
  the 
  distant 
  

   past. 
  That 
  the 
  vulcanism 
  of 
  the 
  present 
  period 
  stands 
  in 
  close 
  

   temporal 
  connection 
  with 
  the 
  Alpidian 
  folding 
  period 
  should 
  in 
  no 
  

   way 
  be 
  taken 
  as 
  prejudicing 
  its 
  dying 
  out 
  in 
  our 
  comparison 
  of 
  the 
  

   activities 
  of 
  the 
  geological 
  past. 
  

  

  Into 
  whatever 
  class 
  of 
  geological 
  activity 
  we 
  probe, 
  in 
  no 
  case 
  are 
  

   we 
  led 
  to 
  the 
  conclusion 
  that 
  evidence 
  from 
  the 
  expressed 
  move- 
  

   ments 
  indicates 
  an 
  on-coming 
  senility 
  of 
  the 
  earth. 
  Everywhere 
  

   rhythmical 
  rising 
  and 
  falling, 
  there 
  is 
  nowhere 
  a 
  continuous 
  decrease 
  

   of 
  the 
  curve 
  of 
  force. 
  Although 
  these 
  rhythms 
  in 
  the 
  life 
  of 
  the 
  

   earth 
  are 
  so 
  distinctly 
  recognized, 
  their 
  cause 
  is 
  still 
  to-day 
  an 
  

   unsolved 
  riddle. 
  Cosmical 
  relations 
  are 
  recognized 
  only 
  in 
  limited 
  

   amounts 
  and 
  undetermined 
  significance 
  ; 
  or 
  are 
  the 
  causes 
  within 
  the 
  

   earth 
  itself? 
  

  

  Joly 
  only 
  recently 
  estimated 
  the 
  relations 
  between 
  radioactive 
  

   transformations 
  and 
  geological 
  phenomena. 
  He 
  sketched 
  in 
  bold 
  

   strokes 
  a 
  picture 
  showing 
  how 
  this 
  secret 
  force 
  of 
  radioactivity 
  could 
  

   broadly 
  account 
  for 
  these 
  rhythms, 
  the 
  " 
  revolutions 
  " 
  of 
  the 
  building 
  

   of 
  mountains 
  through 
  folding 
  and 
  the 
  great 
  movements 
  of 
  the 
  masses 
  

   of 
  the 
  earth's 
  crust. 
  It 
  does 
  not 
  lie 
  within 
  my 
  tas]c 
  to-day 
  to 
  go 
  into 
  

   his 
  arguments, 
  the 
  only 
  purpose 
  of 
  which 
  would 
  be 
  to 
  emphasize 
  the 
  

   rhythmical 
  nature 
  of 
  the 
  geological 
  events 
  for 
  the 
  understanding 
  of 
  

   the 
  geological 
  " 
  life 
  " 
  of 
  the 
  earth 
  which 
  we 
  have 
  been 
  discussing. 
  

  

  If 
  really 
  in 
  the 
  radioactive 
  processes 
  is 
  to 
  be 
  found 
  the 
  " 
  magic 
  " 
  

   Avhich 
  might 
  be 
  the 
  unique 
  causation 
  factor 
  for 
  these 
  manifestations 
  

   of 
  the 
  life 
  of 
  our 
  earth, 
  then 
  under 
  the 
  circumstances 
  maj?^ 
  we 
  not 
  

   wholly 
  lay 
  aside 
  the 
  idea 
  of 
  any 
  aging 
  of 
  the 
  earth 
  as 
  interpreted 
  in 
  

   these 
  pulses 
  of 
  the 
  earth's 
  crust 
  ? 
  If 
  the 
  physical 
  relations 
  within 
  the 
  

   earth's 
  crust, 
  which 
  Joly 
  assumed 
  in 
  the 
  compensating 
  processes 
  rela- 
  

   tive 
  to 
  the 
  development 
  of 
  radioactive 
  energy, 
  do 
  not 
  occur 
  with 
  the 
  

   complete 
  balance 
  that 
  Joly 
  assumes, 
  if 
  there 
  would 
  occur 
  a 
  storing 
  up 
  

   of 
  energy 
  beneath 
  the 
  earth's 
  crust 
  and 
  within 
  the 
  earth's 
  body, 
  then 
  

   a 
  crippling 
  of 
  the 
  earth's 
  pulses 
  would 
  be 
  rendered 
  impossible. 
  In- 
  

   stead, 
  then, 
  of 
  becoming 
  a 
  crippled 
  earth, 
  of 
  becoming 
  stiff 
  in 
  its 
  

   actions, 
  may 
  it 
  not 
  rather 
  be 
  going 
  toward 
  the 
  catastrophe 
  of 
  a 
  

   '•Nova"? 
  

  

  