﻿242 
  

  

  Dr. 
  W. 
  B. 
  Carpenter 
  on 
  the 
  Nature 
  of 
  the 
  [Feb. 
  4, 
  

  

  voyage 
  from 
  St. 
  Thomas 
  to 
  Bermuda), 
  as 
  well 
  as 
  in 
  the 
  next 
  two 
  sound- 
  

   ings 
  of 
  2960 
  and 
  2800 
  fathoms 
  respectively 
  (the 
  average 
  of 
  the 
  three 
  

   beiug 
  3211 
  fathoms), 
  the 
  bottom 
  was 
  " 
  grey 
  ooze 
  ; 
  " 
  whilst 
  in 
  the 
  next 
  

   three 
  soundings 
  of 
  2850, 
  2700, 
  and 
  2600 
  fathoms 
  respectively 
  (the 
  ave- 
  

   rage 
  of 
  the 
  three 
  being 
  2716 
  fathoms, 
  or 
  nearly 
  400 
  fathoms 
  less 
  than 
  the 
  

   preceding) 
  the 
  bottom 
  was 
  of 
  " 
  red 
  clay." 
  Between 
  Bermuda 
  and 
  the 
  

   Azores, 
  again, 
  there 
  were 
  six 
  successive 
  soundings 
  between 
  2700 
  and 
  

   2875 
  fathoms, 
  in 
  which 
  the 
  bottom 
  was 
  " 
  grey 
  ooze.". 
  

  

  It 
  is 
  clear, 
  then, 
  that 
  no 
  constant 
  relation 
  exists 
  between 
  depth 
  and 
  

   the 
  nature 
  of 
  the 
  bottom. 
  If 
  not 
  only 
  eight 
  ordinary 
  soundings 
  whose 
  

   average 
  was 
  almost 
  exactly 
  2800 
  fathoms, 
  but 
  the 
  extraordinarily 
  deep 
  

   sounding 
  of 
  3875 
  fathoms, 
  gave 
  a 
  bottom 
  of 
  " 
  grey 
  ooze," 
  it 
  surely 
  can- 
  

   not 
  be 
  "an 
  ascertained 
  fact 
  that 
  wherever 
  the 
  depth, 
  increases 
  from 
  

   about 
  2200 
  to 
  2600 
  fathoms, 
  the 
  modern 
  chalk 
  formation 
  of 
  the 
  Atlantic 
  

   and 
  other 
  oceans 
  passes 
  into 
  a 
  clay." 
  

  

  Now 
  if 
  this 
  " 
  red 
  clay 
  " 
  had 
  the 
  character 
  of 
  an 
  ordinary 
  river-silt, 
  

   it 
  would 
  be 
  quite 
  conformable 
  to 
  my 
  Mediterranean 
  experience 
  to 
  regard 
  

   it 
  (as 
  Prof. 
  Wyville 
  Thomson 
  himself 
  was 
  at 
  first 
  disposed 
  to 
  do) 
  in 
  the 
  

   light 
  of 
  a 
  derivative 
  from 
  the 
  land, 
  diffused 
  through 
  the 
  ocean-water 
  

   and 
  slowly 
  settling-down 
  over 
  particular 
  areas, 
  to 
  which 
  it 
  might 
  be 
  de- 
  

   termined 
  by 
  the 
  prevalent 
  direction 
  of 
  the 
  bottom-flow, 
  which 
  would 
  

   greatly 
  depend 
  in 
  its 
  turn 
  upon 
  the 
  ridge-and- 
  valley 
  conformation 
  of 
  the 
  

   sea-bed. 
  And 
  the 
  presence 
  of 
  a 
  small 
  proportion 
  of 
  this 
  material 
  in 
  the 
  

   ordinary 
  Globigerina-ooze, 
  whilst, 
  where 
  it 
  is 
  deposited 
  in 
  quantity, 
  there 
  

   are 
  neither 
  entire 
  Globigerince 
  nor 
  their 
  disintegrated 
  remains, 
  would 
  be 
  

   perfectly 
  consistent 
  with 
  the 
  known 
  destructive 
  effect 
  of 
  the 
  slow 
  sub- 
  

   sidence 
  of 
  a 
  muddy 
  sediment 
  on 
  many 
  forms 
  of 
  animal 
  life*. 
  

  

  But 
  I 
  agree 
  with 
  Prof. 
  Wyville 
  Thomson 
  in 
  thinking 
  that 
  the 
  remark- 
  

   able 
  uniformity 
  of 
  this 
  deposit, 
  coupled 
  with 
  its 
  peculiar 
  composition, 
  in- 
  

   dicates 
  a 
  different 
  derivation 
  ; 
  and 
  the 
  suggestion 
  I 
  have 
  to 
  offer 
  is 
  based 
  

   on 
  its 
  near 
  relation 
  in 
  composition, 
  notwithstanding 
  its 
  great 
  difference 
  

   in 
  appearance, 
  to 
  Glauconite 
  — 
  the 
  mineral 
  of 
  which 
  the 
  green 
  sands 
  

   that 
  occur 
  in 
  various 
  Geological 
  formations 
  are 
  for 
  the 
  most 
  part 
  com- 
  

   posed, 
  and 
  which 
  is 
  a 
  silicate 
  of 
  peroxide 
  of 
  iron 
  and 
  alumina. 
  

  

  It 
  is 
  well 
  known 
  that 
  Prof. 
  Ehrenberg, 
  in 
  1853 
  f 
  , 
  drew 
  attention 
  to 
  

   the 
  fact 
  that 
  the 
  grains 
  of 
  these 
  green 
  sands 
  are 
  for 
  the 
  most 
  part, 
  if 
  not 
  

   entirely, 
  internal 
  casts 
  of 
  Poraminif 
  era 
  — 
  the 
  sarcodic 
  bodies 
  of 
  the 
  animals 
  

   having 
  been 
  replaced 
  by 
  glauconite, 
  and 
  the 
  calcareous 
  shells 
  subsequently 
  

   got 
  rid 
  of, 
  either 
  by 
  abrasion 
  or 
  by 
  some 
  solvent 
  which 
  does 
  not 
  attack 
  

   their 
  contents. 
  It 
  was 
  soon 
  afterwards 
  shown 
  by 
  Prof. 
  Bailey 
  (U. 
  S.) 
  

   that 
  in 
  certain 
  localities 
  a 
  like 
  replacement 
  is 
  going 
  on 
  at 
  the 
  present 
  

   time, 
  the 
  chambers 
  of 
  recent 
  Poraminif 
  era 
  being 
  occasionally 
  found 
  to 
  be 
  

  

  * 
  See 
  my 
  ' 
  Shearwater 
  ' 
  Report 
  in 
  Proceed. 
  Roy. 
  Soc. 
  1872, 
  vol. 
  xx. 
  p. 
  584. 
  

   t 
  " 
  TJeber 
  den 
  Grunsand 
  und 
  seine 
  Erlauterung 
  des 
  organischen 
  Lebens," 
  in 
  Abhandl. 
  

   der 
  konigl. 
  Akad. 
  der 
  Wissensch. 
  zu 
  Berlin, 
  1855, 
  p. 
  85. 
  

  

  