﻿226 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  and, 
  according 
  to 
  Murray's 
  description 
  (1912, 
  p. 
  162), 
  usually 
  oc- 
  

   curs 
  "off 
  high 
  and 
  bold 
  coasts 
  where 
  currents 
  from 
  different 
  sources 
  

   alternate 
  with 
  the 
  season, 
  as 
  off 
  £he 
  Cape 
  of 
  Good 
  Hope, 
  off 
  the 
  east 
  

   coast 
  of 
  Australia, 
  off 
  Japan, 
  and 
  off 
  the 
  Atlantic 
  coasts 
  of 
  the 
  

   United 
  States." 
  It 
  may 
  grade 
  into 
  greensands. 
  Red 
  mud 
  is 
  still 
  

   another 
  variety 
  "found 
  in 
  the 
  Yellow 
  Sea 
  and 
  off 
  the 
  coast 
  of 
  Brazil, 
  

   where 
  the 
  great 
  rivers 
  bring 
  down 
  a 
  large 
  amount 
  of 
  ochreous 
  mat- 
  

   ter" 
  * 
  * 
  * 
  (1912, 
  p. 
  162). 
  Volcanic 
  mud 
  and 
  coral 
  mud 
  are 
  

   self-explanatory. 
  

  

  Pelagic 
  deposits 
  begin 
  to 
  make 
  their 
  appearance 
  in 
  the 
  ocean 
  basins 
  

   proper, 
  at 
  sufficient 
  distances 
  from 
  the 
  continental 
  margins 
  to 
  prevent 
  

   their 
  being 
  masked 
  by 
  detritus 
  from 
  the 
  land. 
  Of 
  these, 
  Globigerina 
  

   ooze 
  is 
  the 
  most 
  widely 
  distributed. 
  Diatom 
  ooze 
  is 
  characteristic 
  of 
  

   the 
  colder 
  waters, 
  particularly 
  the 
  great 
  circumpolar 
  seas 
  of 
  the 
  

   Southern 
  Hemisphere; 
  pteropod" 
  ooze 
  is 
  found 
  in 
  the 
  warm 
  waters 
  

   of 
  the 
  Tropics 
  ; 
  and 
  radiolarian 
  ooze 
  occurs 
  in 
  the 
  deeper 
  parts 
  of 
  the 
  

   Pacific 
  and 
  Indian 
  Oceans. 
  The 
  last 
  and 
  most 
  interesting 
  of 
  the 
  

   deep-sea 
  oozes 
  is 
  red 
  clay, 
  which 
  floors 
  vast 
  areas 
  of 
  the 
  Pacific 
  far 
  

   from 
  the 
  continents. 
  It 
  is 
  supposed, 
  according 
  to 
  Murray, 
  to 
  be 
  a 
  

   hydrated 
  silicate 
  of 
  alumina 
  derived 
  from 
  the 
  disintergration 
  of 
  

   pumice 
  and 
  volcanic 
  ash. 
  Its 
  rate 
  of 
  deposition 
  is 
  extremely 
  slow, 
  

   and 
  consequently 
  it 
  is 
  found 
  only 
  in 
  the 
  more 
  remote 
  parts 
  of 
  the 
  

   ocean 
  where 
  the 
  deposition 
  of 
  other 
  debris 
  and 
  planktonic 
  material 
  

   is 
  practically 
  zero. 
  

  

  Such, 
  in 
  general, 
  is 
  the 
  horizontal 
  distribution 
  of 
  the 
  various 
  types 
  

   of 
  marine 
  sediments 
  as 
  determined 
  from 
  the 
  Challenger's 
  data. 
  Sub- 
  

   sequent 
  expeditions 
  merely 
  defined 
  the 
  areas 
  more 
  exactly. 
  It 
  was 
  

   worked 
  out, 
  in 
  a 
  sense, 
  merely 
  as 
  a 
  byproduct 
  of 
  sounding. 
  The 
  

   samples, 
  as 
  we 
  have 
  seen, 
  consisted 
  of 
  small 
  plugs 
  of 
  mud 
  brought 
  up 
  

   sticking 
  in 
  the 
  end 
  of 
  the 
  sounding 
  tube, 
  and 
  they 
  were 
  so 
  short 
  that 
  

   to 
  all 
  intents 
  and 
  purposes 
  they 
  were 
  surface 
  samples. 
  During 
  this 
  

   period 
  no 
  one 
  seems 
  to 
  have 
  made 
  any 
  serious 
  attempt 
  to 
  secure 
  cores. 
  

  

  IMPROVEMENTS 
  IN 
  SOUNDING 
  TECHNIQUE 
  

  

  The 
  gear 
  for 
  deep-water 
  sounding 
  had 
  been 
  greatly 
  improved 
  as 
  

   time 
  went 
  on, 
  and 
  with 
  this 
  development 
  in 
  technique 
  came 
  a 
  cor- 
  

   responding 
  increase 
  in 
  our 
  knowledge 
  of 
  the 
  true 
  configuration 
  of 
  the 
  

   ocean 
  basins. 
  When 
  deep 
  soundings 
  were 
  first 
  undertaken, 
  an 
  at- 
  

   tempt 
  was 
  made 
  to 
  haul 
  up 
  the 
  whole 
  sounding 
  lead. 
  Consequently 
  

   a 
  heavy 
  line 
  was 
  necessary 
  and, 
  when 
  any 
  considerable 
  length 
  was 
  out, 
  

   its 
  weight 
  bore 
  so 
  close 
  a 
  ratio 
  to 
  that 
  of 
  the 
  sinker 
  that 
  in 
  deep 
  water 
  

   it 
  was 
  impossible 
  to 
  tell 
  when 
  bottom 
  had 
  been 
  reached. 
  Further- 
  

   more, 
  the 
  line 
  kept 
  running 
  out 
  endlessly 
  of 
  its 
  own 
  momentum 
  even 
  

   after 
  the 
  sinker 
  had 
  touched. 
  On 
  the 
  early 
  charts, 
  for 
  instance, 
  some 
  

  

  