﻿[11] 
  ON 
  DEEP-SEA 
  DEPOSITS. 
  7G9 
  

  

  contains 
  fragments 
  of 
  rocks 
  2 
  cm 
  in 
  diameter 
  ; 
  generally, 
  however, 
  the 
  

   minerals, 
  which 
  are 
  derived 
  from 
  the 
  continents 
  and 
  are 
  found 
  mixed 
  

   up 
  with 
  the 
  muddy 
  matter 
  in 
  these 
  deposits, 
  have 
  a 
  diameter 
  of 
  0.5 
  mm 
  

   and 
  less. 
  Quartz 
  particles, 
  often 
  rounded, 
  play 
  the 
  principal 
  part; 
  

   next 
  come 
  mica, 
  feldspar, 
  augite, 
  hornblende, 
  and 
  all 
  the 
  mineral 
  species 
  

   which 
  come 
  from 
  the 
  disintegration 
  of 
  the 
  neighboring 
  lands, 
  or 
  the 
  

   lands 
  traversed 
  by 
  rivers 
  which 
  enter 
  the 
  sea 
  near 
  the 
  place 
  where 
  

   the 
  specimens 
  have 
  been 
  collected. 
  These 
  minerals 
  make 
  up 
  the 
  princi- 
  

   pal 
  and 
  characteristic 
  portion 
  of 
  bine 
  muds, 
  sometimes 
  forming 
  SO 
  per 
  

   cent, 
  of 
  the 
  whole 
  deposit. 
  Glauconite, 
  though 
  generally 
  present, 
  is 
  

   never 
  abundant 
  in 
  blue 
  muds. 
  The 
  remains 
  of 
  calcareous 
  organisms 
  

   are 
  at 
  times 
  quite 
  absent, 
  but 
  occasionally 
  they 
  form 
  over 
  50 
  per 
  cent. 
  

   The 
  latter 
  is 
  the 
  case 
  when 
  the 
  specimen 
  is 
  taken 
  at 
  a 
  considerable 
  dis- 
  

   tance 
  from 
  the 
  coast 
  and 
  at 
  a 
  moderate 
  depth. 
  These 
  calcareous 
  frag- 
  

   ments 
  consist 
  of 
  bottom-living 
  and 
  pelagic 
  Foraminifera, 
  Mollusks, 
  Poly- 
  

   zoa, 
  Serpuloe, 
  Echinoderms, 
  Alcyonarian-spicules, 
  Corals, 
  &c. 
  The 
  re- 
  

   mains 
  of 
  Diatoms 
  and 
  Kadiolarians 
  are 
  usually 
  present. 
  Generally 
  

   speaking, 
  as 
  we 
  approach 
  the 
  shore 
  the 
  pelagic 
  organisms 
  disappear, 
  

   and, 
  on 
  the 
  contrary, 
  as 
  we 
  proceed 
  seawards, 
  the 
  size 
  of 
  the 
  mineral 
  

   grains 
  diminishes, 
  and 
  the 
  remains 
  of 
  shore 
  and 
  coast 
  organisms 
  give 
  

   place 
  to 
  pelagic 
  ones, 
  till 
  finally 
  a 
  blue 
  mud 
  passes 
  into 
  a 
  true 
  deep-sea 
  

   deposit. 
  In 
  those 
  regions 
  of 
  the 
  ocean 
  affected 
  with 
  floating 
  ice 
  the 
  

   color 
  of 
  these 
  deposits 
  becomes 
  gray 
  rather 
  than 
  blue 
  at 
  great 
  distances 
  

   from 
  land, 
  and 
  is 
  further 
  modified 
  by 
  the 
  presence 
  of 
  a 
  greater 
  or 
  less 
  

   abundance 
  of 
  glaciated 
  blocks 
  and 
  fragments 
  of 
  quartz. 
  

  

  Green 
  muds 
  and 
  sands. 
  — 
  As 
  regards 
  their 
  origin, 
  composition, 
  and 
  dis- 
  

   tribution 
  near 
  the 
  shores 
  of 
  continental 
  land, 
  these 
  muds 
  and 
  sands 
  

   resemble 
  the 
  blue 
  muds. 
  They 
  are 
  largely 
  composed 
  of 
  argillaceous 
  

   matter 
  and 
  mineral 
  particles 
  of 
  the 
  same 
  size 
  and 
  nature 
  as 
  in 
  the 
  blue 
  

   muds. 
  Their 
  chief 
  characteristic 
  is 
  the 
  presence 
  of 
  a 
  considerable 
  

   quantity 
  of 
  glauconitic 
  grains, 
  either 
  isolated 
  or 
  united 
  into 
  concre- 
  

   tions... 
  In 
  the 
  latter 
  case 
  the 
  grains 
  are 
  cemented 
  together 
  by 
  a 
  brown 
  

   argillaceous 
  matter, 
  and 
  include, 
  besides 
  quartz, 
  feldspar, 
  phosphate 
  

   of 
  lime, 
  and 
  other 
  minerals, 
  more 
  or 
  less 
  altered. 
  The 
  Foraminifera 
  and 
  

   fragments 
  of 
  Echinoderms 
  and 
  other 
  organisms 
  in 
  these 
  muds 
  are 
  fre- 
  

   quently 
  filled 
  with 
  glauconitic 
  substance, 
  and 
  beautiful 
  casts 
  of 
  these 
  

   organisms 
  remain 
  after 
  treatment 
  with 
  weak 
  acid. 
  At 
  times 
  there 
  are 
  

   few 
  calcareous 
  organisms 
  in 
  these 
  deposits, 
  and 
  at 
  other 
  times 
  the 
  re- 
  

   mains 
  of 
  diatoms 
  and 
  radiolariaus 
  are 
  abundant. 
  When 
  these 
  muds 
  

   are 
  dried 
  they 
  become 
  earthy 
  and 
  of 
  a 
  gray-green 
  color. 
  They 
  fre- 
  

   quently 
  give 
  out 
  a 
  sulphureted 
  hydrogen 
  odor. 
  The 
  green 
  color 
  ap- 
  

   pears 
  sometimes 
  to 
  be 
  due 
  to 
  the 
  presence 
  of 
  organic 
  matter, 
  probably 
  

   of 
  vegetable 
  origin, 
  and 
  to 
  the 
  reduction 
  of 
  peroxide 
  of 
  iron 
  to 
  protoxide 
  

   under 
  its 
  influence. 
  The 
  green 
  sands 
  differ 
  from 
  the 
  muds 
  only 
  in 
  the 
  

   comparative 
  absence 
  of 
  the 
  argillaceous 
  and 
  other 
  amorphous 
  matter, 
  

   S. 
  Mis. 
  70 
  40 
  

  

  