﻿328 
  V 
  err 
  ill 
  — 
  Notes 
  on 
  the 
  Geology 
  of 
  the 
  Bermudas. 
  

  

  Beelevatio7i 
  of 
  the 
  Bermudas. 
  Fig. 
  7. 
  

  

  The 
  evidence 
  in 
  regard 
  to 
  the 
  reelevation 
  of 
  the 
  islands 
  

   after 
  their 
  greatest 
  depression 
  is 
  not 
  entirely 
  conclusive. 
  

   Professor 
  Pice 
  adopted 
  the 
  view 
  that 
  such 
  an 
  elevation, 
  of 
  

   small 
  amount, 
  has 
  taken 
  place, 
  but 
  Mr. 
  Agassiz 
  took 
  the 
  oppo- 
  

   site 
  view. 
  At 
  most, 
  the 
  elevation 
  was 
  not 
  over 
  12 
  to 
  15 
  feet. 
  

  

  The 
  evidence 
  depends 
  partly 
  upon 
  the 
  existence 
  of 
  local 
  

   beach 
  deposits, 
  containing 
  existing 
  marine 
  shells, 
  at 
  various 
  

   localities, 
  as 
  at 
  Ireland 
  Island, 
  described 
  in 
  detail 
  by 
  Professor 
  

   Pice. 
  The 
  most 
  elevated 
  beds 
  of 
  this 
  kind 
  are 
  not 
  over 
  15 
  

   feet 
  above 
  the 
  sea. 
  Mr. 
  Agassiz 
  suggests 
  that 
  such 
  deposits 
  

   could 
  have 
  been 
  thrown 
  by 
  storm 
  waves 
  to 
  such 
  heights, 
  and 
  

   therefore 
  that 
  they 
  do 
  not 
  prove 
  elevation. 
  This 
  is 
  no 
  doubt 
  

   true 
  in 
  exposed 
  situations, 
  but 
  some 
  of 
  these 
  beds 
  are 
  situated 
  

   in 
  partially 
  sheltered 
  harbors 
  where 
  such 
  violent 
  wave-action 
  

   would 
  probably 
  not 
  occur. 
  It 
  appears 
  to 
  me 
  probable 
  that 
  part 
  

   of 
  these 
  beds 
  were 
  made 
  just 
  below 
  sea-level, 
  or 
  between 
  tides, 
  

   and 
  therefore 
  do 
  actually 
  give 
  evidence 
  of 
  elevation. 
  That 
  

   they 
  are 
  not 
  more 
  extensive 
  and 
  general 
  may 
  be 
  due 
  partly 
  to 
  

   the 
  abruptness 
  of 
  the 
  shores 
  in 
  most 
  places, 
  and 
  partly 
  to 
  sub- 
  

   sequent 
  erosion. 
  Still 
  we 
  should 
  expect 
  to 
  find 
  many 
  such 
  

   deposits 
  around 
  the 
  low 
  shores 
  of 
  the 
  land-locked 
  bays 
  and 
  

   lagoons, 
  where 
  they 
  are 
  not 
  known 
  to 
  exist, 
  had 
  such 
  a 
  general 
  

   elevation 
  taken 
  place, 
  even 
  to 
  the 
  extent 
  of 
  5 
  or 
  6 
  feet. 
  

  

  Another 
  reason 
  for 
  thinking 
  that 
  an 
  elevation 
  of 
  several 
  feet 
  

   has 
  occurred 
  is 
  the 
  peculiar 
  character 
  of 
  the 
  erosion 
  on 
  many 
  

   of 
  the 
  cliffs, 
  for 
  a 
  second 
  very 
  marked 
  plane 
  of 
  maximum 
  

   erosion 
  can 
  often 
  be 
  observed 
  6 
  to 
  10 
  feet 
  above 
  the 
  one 
  situ- 
  

   ated 
  at 
  or 
  a 
  little 
  above 
  the 
  present 
  high-tide 
  level. 
  In 
  many 
  

   cases 
  the 
  cliffs 
  are 
  thus 
  undercut 
  at 
  two 
  levels. 
  In 
  other 
  cases 
  

   cavernous 
  places 
  or 
  "ovens" 
  of 
  large 
  size 
  have 
  been 
  excavated 
  

   entirely 
  above 
  the 
  reach 
  of 
  ordinary 
  waves. 
  This 
  is 
  the 
  case 
  

   on 
  the 
  islands 
  in 
  land-locked 
  Harrington 
  Sound 
  as 
  well 
  as 
  in 
  

   more 
  exposed 
  situations. 
  It 
  seems 
  hardly 
  probable 
  that 
  occa- 
  

   sional 
  severe 
  storms 
  could 
  effect 
  this 
  kind 
  of 
  erosion 
  at 
  such 
  

   elevations. 
  (Fig. 
  7.) 
  This 
  upper 
  zone 
  of 
  erosion 
  has 
  appar- 
  

   ently 
  been 
  mostly 
  removed 
  by 
  subsequent 
  erosion 
  on 
  the 
  more 
  

   exposed 
  cliffs, 
  especially 
  on 
  the 
  south 
  side. 
  

  

  Nature 
  and 
  Origin 
  of 
  the 
  . 
  White 
  Sands. 
  Figs. 
  8, 
  9. 
  

   Most 
  writers 
  have 
  spoken 
  of 
  the 
  white 
  sand 
  of 
  the 
  beaches 
  

   and 
  lagoons 
  as 
  "coral 
  sand." 
  Mr. 
  A. 
  Agassiz 
  considered 
  it 
  as 
  

   chiefly 
  derived 
  from 
  the 
  erosion 
  of 
  the 
  limestone 
  rocks 
  of 
  the 
  

   shores. 
  If 
  this 
  were 
  the 
  case, 
  it 
  would 
  imjoly 
  a 
  rapid 
  decrease 
  

   in 
  the 
  total 
  mass 
  of 
  the 
  islands, 
  for 
  much 
  of 
  the 
  finer 
  sand 
  and 
  

   mud 
  in 
  shallow 
  water 
  is 
  stirred 
  up 
  by 
  storms, 
  and 
  then 
  is 
  con- 
  

  

  