﻿350 
  W. 
  G. 
  Foye 
  — 
  Geology 
  of 
  the 
  Lau 
  Islands. 
  

  

  observations 
  of 
  the 
  writer 
  are 
  correct 
  the 
  growing 
  reef 
  is 
  con- 
  

   tinually 
  being 
  destroyed 
  and 
  its 
  debris 
  cast 
  into 
  the 
  lagoon 
  ; 
  

   the 
  reef 
  grows 
  on 
  a 
  mass 
  of 
  its 
  own 
  waste 
  containing 
  only 
  a 
  

   limited 
  number 
  of 
  coral 
  heads 
  in 
  situ. 
  There 
  is 
  more 
  chance 
  

   of 
  the 
  rounded 
  heads 
  of 
  the 
  lagoon 
  being 
  preserved 
  than 
  the 
  

   fungus-like 
  growth 
  of 
  the 
  reef-edge. 
  

  

  There 
  is, 
  therefore, 
  positive 
  evidence 
  of 
  subsidence 
  in 
  the 
  

   Lau 
  islands, 
  and 
  very 
  good 
  evidence 
  that 
  barrier 
  reefs 
  and 
  

   atolls 
  were 
  developed 
  during 
  such 
  subsidence. 
  Thus 
  far 
  the 
  

   Darwinian 
  theory 
  is 
  supported, 
  but 
  the 
  irregular 
  uplifts 
  and 
  

   subsidences 
  negative 
  the 
  idea 
  of 
  a 
  general 
  depression 
  of 
  the 
  

   Pacific 
  islands, 
  a 
  further 
  conception 
  of 
  the 
  theory. 
  The 
  earth 
  

   movements 
  are 
  here 
  irregular 
  and 
  seem 
  to 
  be 
  confined 
  to 
  indi- 
  

   vidual 
  foci 
  whose 
  instability 
  is 
  the 
  result 
  of 
  isostatic 
  adjustment 
  

   of 
  large 
  fault 
  blocks, 
  of 
  secular 
  cooling 
  after 
  volcanism, 
  or 
  of 
  

   the 
  transfer 
  of 
  large 
  quantities 
  of 
  molten 
  rock 
  from 
  the 
  

   interior 
  to 
  the 
  exterior 
  of 
  the 
  earth's 
  crust. 
  

  

  There 
  is 
  another 
  method 
  by 
  which 
  atolls 
  develop. 
  The 
  

   limestone 
  islands 
  are 
  rapidly 
  eroded 
  to 
  sea-level 
  by 
  atmospheric 
  

   solution. 
  Evidence 
  of 
  this 
  process 
  may 
  be 
  seen 
  in 
  the 
  diminish- 
  

   ing 
  limestone 
  masses 
  within 
  the 
  lagoons 
  of 
  many 
  of 
  the 
  Lau 
  

   islands. 
  By. 
  tidal-scour 
  and 
  wave 
  action, 
  platforms 
  are 
  developed 
  

   slightly 
  below 
  sea-level. 
  Examples 
  of 
  such 
  platforms 
  may 
  be 
  

   seen 
  about 
  Fulanga 
  and 
  Ongea. 
  It 
  is 
  significant, 
  however, 
  that 
  

   most 
  of 
  these 
  islands 
  have 
  lagoons 
  10 
  to 
  15 
  fathoms 
  in 
  depth. 
  

   Such 
  depths 
  cannot 
  be 
  ascribed 
  to 
  erosion 
  but 
  must 
  be 
  the 
  

   result 
  of 
  recent 
  submergence. 
  In 
  time, 
  the 
  erosion 
  of 
  the 
  

   elevated 
  limestone 
  of 
  Fulanga 
  will 
  lead 
  to 
  the 
  development 
  of 
  

   an 
  atoll 
  of 
  the 
  second 
  generation 
  replacing 
  the 
  older 
  uplifted 
  

   mass. 
  

  

  In 
  conclusion, 
  it 
  should 
  be 
  stated 
  that 
  the 
  evidence 
  from 
  the 
  

   unstable 
  islands 
  of 
  the 
  Lau 
  Group 
  should 
  not 
  be 
  given 
  too 
  

   wide 
  application. 
  The 
  writer 
  is 
  convinced 
  that 
  the 
  Glacial- 
  

   control 
  theory 
  has 
  a 
  large 
  body 
  of 
  facts 
  in 
  its 
  favor 
  but 
  these 
  

   facts 
  are 
  gathered 
  from 
  other, 
  more 
  stable, 
  portions 
  of 
  the 
  

   earth's 
  surface. 
  

  

  Middlebury 
  College, 
  Middlebury, 
  Vt. 
  

  

  