﻿[23] 
  ON 
  DEEP-SEA 
  DEPOSITS. 
  781 
  

  

  serve 
  in 
  considerable 
  quantities 
  in 
  the 
  clay 
  of 
  the 
  center 
  of 
  the 
  Pacific, 
  

   have 
  been 
  formed 
  at 
  the 
  expense 
  of 
  the 
  decomposing 
  volcanic 
  matters 
  

   spread 
  out 
  upon 
  the 
  bed 
  of 
  that 
  ocean. 
  

  

  In 
  connection 
  with 
  this 
  formation 
  of 
  zeolites 
  reference 
  may 
  be 
  made 
  

   to 
  a 
  chemical 
  process 
  whose 
  principal 
  seat 
  is 
  the 
  red-clay 
  areas, 
  and 
  

   which 
  gives 
  rise 
  to 
  nodules 
  of 
  manganiferous 
  iron. 
  This 
  substance 
  is 
  

   almost 
  universally 
  distributed 
  in 
  oceanic 
  sediments 
  ; 
  yet 
  it 
  is 
  not 
  so 
  

   much 
  of 
  the 
  areas 
  of 
  its 
  abundance 
  that 
  we 
  intend 
  to 
  speak 
  as 
  to 
  the 
  

   fact 
  of 
  its 
  occurrence 
  in 
  the 
  red 
  clay, 
  because 
  this 
  association 
  tends 
  to 
  

   show 
  a 
  common 
  relation 
  of 
  origin. 
  It 
  is' 
  exactly 
  in 
  those 
  regions 
  where 
  

   there 
  is 
  an 
  accumulation 
  of 
  pyroxenic 
  lavas 
  in 
  decomposition, 
  contain- 
  

   ing 
  silicates 
  with 
  a 
  base 
  of 
  manganese 
  and 
  iron, 
  such, 
  for 
  example, 
  as 
  

   augite, 
  hornblende, 
  olivine, 
  magnetite, 
  and 
  basic 
  glasses, 
  that 
  manganese 
  

   nodules 
  occur 
  in 
  greatest 
  numbers. 
  In 
  the 
  regions 
  where 
  the 
  sedimen- 
  

   tary 
  action, 
  mechanical 
  and 
  organic, 
  as 
  it 
  were, 
  suspended, 
  and 
  where, 
  

   as 
  will 
  appear 
  in 
  the 
  sequel, 
  everything 
  shows 
  an 
  extreme 
  slowness 
  of 
  

   deposition, 
  in 
  these 
  calm 
  waters, 
  favorable 
  to 
  chemical 
  reactions, 
  ferro- 
  

   manganiferous 
  substances 
  form 
  concretions 
  around 
  organic 
  and 
  inor- 
  

   ganic 
  centers. 
  

  

  These 
  concentrations 
  of 
  ferric 
  and 
  manganic 
  oxides, 
  mixed 
  with 
  ar- 
  

   gillaceous 
  materials 
  whose 
  form 
  and 
  dimensions 
  are 
  extremely 
  varia- 
  

   ble, 
  belong 
  generally 
  to 
  the 
  earthy 
  variety 
  or 
  wad, 
  but 
  pass 
  sometimes, 
  

   though 
  rarely, 
  into 
  varieties 
  of 
  hydrated 
  oxide 
  of 
  manganese, 
  with 
  dis- 
  

   tinct 
  indications 
  of 
  radially 
  fibrous 
  crystallization. 
  The 
  interpretation 
  

   to 
  which 
  we 
  are 
  led 
  in 
  order 
  to 
  explain 
  this 
  formation 
  of 
  manganese 
  

   nodules 
  is 
  the 
  same 
  as 
  that 
  which 
  is 
  admitted 
  in 
  explanation 
  of 
  the 
  

   formation 
  of 
  coatings 
  of 
  this 
  material 
  on 
  the 
  surface 
  of 
  terrestrial 
  rocks. 
  

   These 
  salts 
  of 
  manganese 
  and 
  iron, 
  dissolved 
  in 
  water 
  by 
  carbonic 
  

   acid, 
  then 
  precipitated 
  in 
  the 
  form 
  of 
  carbonate 
  of 
  protoxide 
  of 
  iron 
  

   and 
  manganese, 
  become 
  oxidized, 
  and 
  give 
  rise 
  in 
  the 
  calm 
  and 
  deep 
  

   oceanic 
  regions 
  to 
  more 
  or 
  less 
  pure 
  ferro-manganiferous 
  concretions. 
  

   At 
  the 
  same 
  time 
  it 
  must 
  be 
  admitted 
  that 
  rivers 
  may 
  bring 
  to 
  the 
  

   ocean 
  a 
  contribution 
  of 
  these 
  same 
  substances. 
  

  

  Among 
  the 
  bodies 
  which, 
  in 
  certain 
  regions 
  where 
  red 
  clay 
  predomi- 
  

   nates, 
  serve 
  as 
  centers 
  for 
  these 
  manganiferous 
  nodules, 
  are 
  the 
  remains 
  

   of 
  vertebrates. 
  These 
  remains 
  are 
  the 
  hardest 
  parts 
  of 
  the 
  skeleton 
  — 
  

   tympanic 
  bones 
  of 
  whales, 
  beaks 
  of 
  Ziphius, 
  teeth 
  of 
  sharks 
  ; 
  and 
  just 
  

   as 
  the 
  calcareous 
  shells 
  are 
  eliminated 
  in 
  the 
  depths, 
  so 
  all 
  the 
  remains 
  

   of 
  the 
  larger 
  vertebrates 
  are 
  absent 
  except 
  the 
  most 
  resistant 
  portions. 
  

   These 
  bones 
  often 
  serve 
  as 
  a 
  center 
  for 
  the 
  manganese-iron 
  concretions, 
  

   being 
  frequently 
  surrounded 
  by 
  layers 
  several 
  centimeters 
  in 
  thickness. 
  

   In 
  the 
  same 
  dredgings 
  in 
  the 
  red-clay 
  areas 
  some 
  sharks' 
  teeth 
  and 
  

   cetacean 
  ear-bones, 
  some 
  of 
  which 
  belong 
  to 
  extinct 
  species, 
  are 
  sur- 
  

   rounded 
  with 
  thick 
  layers 
  of 
  the 
  manganese, 
  and 
  others 
  with 
  merely 
  a 
  

   slight 
  coating. 
  We 
  will 
  make 
  use 
  of 
  these 
  facts 
  to 
  establish 
  the 
  conclu- 
  

   sions 
  which 
  terminate 
  this 
  paper. 
  

  

  