﻿762 
  EEPOET 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [4] 
  

  

  most 
  instances 
  make 
  up 
  deep-sea 
  deposits, 
  render 
  the 
  determinations 
  

   difficult. 
  In 
  spite 
  of 
  the 
  improvements 
  recently 
  effected 
  in 
  the 
  micro- 
  

   scopical 
  examination 
  of 
  minerals, 
  it 
  is 
  impossible 
  to 
  apply 
  all 
  the 
  opti- 
  

   cal 
  resources 
  of 
  the 
  instrument 
  to 
  the 
  determination 
  of 
  the 
  species 
  of 
  ex- 
  

   tremely 
  fine, 
  loose, 
  and 
  fractured 
  particles. 
  Again, 
  the 
  examination 
  of 
  

   these 
  deposits 
  is 
  rendered 
  difficult 
  by 
  the 
  presence 
  of 
  a 
  large 
  quantity 
  

   of 
  amorphous 
  mineral 
  matter, 
  and 
  of 
  shells, 
  skeletons, 
  and 
  minute 
  par- 
  

   ticles 
  of 
  organic 
  origin. 
  It 
  is 
  also 
  to 
  be 
  observed 
  that 
  we 
  have 
  not 
  to 
  

   deal 
  with 
  pure 
  and 
  unaltered 
  mineral 
  fragments, 
  but 
  with 
  particles 
  upon 
  

   which 
  the 
  chemical 
  action 
  of 
  the 
  sea 
  has 
  wrought 
  great 
  changes, 
  and 
  

   more 
  or 
  less 
  destroyed 
  their 
  distinctive 
  characters. 
  

  

  What 
  still 
  further 
  complicates 
  these 
  researches 
  is 
  the 
  endeavor 
  to 
  

   discover 
  the 
  origin 
  of 
  the 
  heterogeneous 
  materials 
  which 
  make 
  up 
  the 
  

   deposits. 
  These 
  have 
  been 
  subjected 
  to 
  the 
  influence 
  of 
  a 
  great 
  number 
  

   of 
  agents, 
  of 
  some 
  of 
  which 
  our 
  knowledge 
  is 
  to 
  a 
  great 
  extent 
  still 
  in 
  

   its 
  infancy. 
  We 
  must 
  take 
  into 
  account 
  a 
  large 
  number 
  of 
  agents 
  and 
  

   processes, 
  such 
  as 
  ocean 
  currents 
  ; 
  the 
  distribution 
  of 
  temperature 
  in 
  

   the 
  water 
  at 
  the 
  surface 
  and 
  at 
  the 
  bottom 
  ; 
  the 
  distribution 
  of 
  organ- 
  

   isms 
  as 
  dependent 
  on 
  temperature 
  and 
  specific 
  gravity 
  of 
  the 
  water 
  ; 
  

   the 
  influence 
  of 
  aerial 
  currents; 
  the 
  carrying 
  power 
  of 
  rivers 
  ; 
  the 
  limit 
  

   of 
  transport 
  by 
  waves 
  ; 
  the 
  eruptions 
  of 
  aerial 
  and 
  submarine 
  volcanoes; 
  

   the 
  effect 
  of 
  glaciers 
  in 
  transporting 
  mineral 
  particles, 
  and, 
  when 
  melt- 
  

   ing, 
  influencing 
  the 
  specific 
  gravity 
  of 
  the 
  water, 
  which 
  in 
  turn 
  affects 
  

   the 
  animal 
  and 
  plant 
  life 
  of 
  the 
  surface. 
  It 
  is 
  necessary 
  to 
  study 
  the 
  

   chemical 
  reactions 
  which 
  take 
  place 
  in 
  great 
  depths 
  ; 
  in 
  short, 
  to 
  call 
  

   to 
  our 
  aid 
  all 
  the 
  assistance 
  which 
  the 
  physical 
  and 
  biological 
  sciences 
  

   can 
  furnish. 
  It 
  will 
  thus 
  be 
  understood 
  that 
  the 
  task, 
  like 
  all 
  first 
  at- 
  

   tempts 
  in 
  a 
  new 
  field, 
  is 
  one 
  of 
  exceptional 
  difficulty, 
  and 
  demands 
  con- 
  

   tinued 
  effort 
  to 
  carry 
  it 
  to 
  a 
  successful 
  issue. 
  

  

  In 
  presenting 
  a 
  short 
  resume 
  of 
  our 
  methods, 
  of 
  the 
  nomenclature 
  we 
  

   have 
  adopted, 
  and 
  of 
  the 
  investigation 
  into 
  the 
  origin 
  of 
  the 
  deposit 
  in 
  

   the 
  deep 
  sea 
  and 
  deeper 
  parts 
  of 
  the 
  littoral 
  zones, 
  we 
  offer 
  it 
  as 
  a 
  sketch 
  

   of 
  our 
  research, 
  prepared 
  to 
  modify 
  the 
  arrangements 
  in 
  any 
  way 
  which 
  

   an 
  intelligent 
  criticism 
  may 
  suggest. 
  

  

  Before 
  proceeding 
  to 
  a 
  description 
  of 
  methods 
  and 
  of 
  the 
  varieties 
  of 
  

   deposits, 
  with 
  their 
  distribution 
  in 
  modern 
  ocean, 
  we 
  will 
  briefly 
  enum- 
  

   erate 
  the 
  materials 
  which 
  our 
  examination 
  has 
  shown 
  to 
  take 
  part 
  in 
  

   the 
  formation 
  of 
  these 
  deposits, 
  state 
  the 
  origin 
  of 
  the 
  material, 
  and 
  

   the 
  agent 
  concerned 
  in 
  their 
  deposition, 
  distribution, 
  and 
  modification. 
  

  

  Materials. 
  — 
  The 
  materials 
  which 
  unite 
  to 
  form 
  the 
  deposits 
  which 
  

   we 
  have 
  to 
  describe 
  may 
  be 
  divided 
  into 
  two 
  groups, 
  viewed 
  in 
  rela- 
  

   tion 
  to 
  their 
  origin, 
  viz, 
  mineral 
  and 
  organic. 
  

  

  The 
  mineral 
  particles 
  carried 
  into 
  the 
  ocean 
  have 
  a 
  different 
  form 
  

   and 
  size, 
  according 
  to 
  the 
  agents 
  which 
  have 
  been 
  concerned 
  in 
  their 
  

   transport. 
  Generally 
  speaking, 
  their 
  size 
  diminishes 
  with 
  distance 
  

   from 
  the 
  coast, 
  but 
  here 
  we 
  limit 
  our 
  remarks 
  to 
  the 
  mineralogical 
  

  

  