﻿780 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [22] 
  

  

  that 
  these 
  argillaceous 
  deposits 
  owe 
  their 
  origin 
  to 
  the 
  inorganic 
  residue 
  

   of 
  the 
  calcareous 
  shells 
  which 
  are 
  dissolved 
  away 
  in 
  deep 
  water, 
  but 
  

   this 
  view 
  has 
  no 
  foundation 
  in 
  fact. 
  Everything 
  seems 
  to 
  show 
  that 
  

   the 
  formation 
  of 
  the 
  clay 
  is 
  due 
  to 
  the 
  decomposition 
  of 
  fragment- 
  

   ary 
  volcanic 
  products, 
  whoso 
  presence 
  can 
  be 
  detected 
  over 
  the 
  whole 
  

   floor 
  of 
  the 
  ocean. 
  

  

  These 
  volcanic 
  materials 
  are 
  derived 
  from 
  floating 
  pumice 
  and 
  vol- 
  

   canic 
  ashes, 
  ejected 
  to 
  great 
  distances 
  by 
  terrestrial 
  volcanoes 
  and 
  car- 
  

   ried 
  far 
  by 
  the 
  winds. 
  It 
  is 
  also 
  known 
  that 
  beds 
  of 
  lava 
  and 
  of 
  tufa 
  are 
  

   laid 
  down 
  upon 
  the 
  bottom 
  of 
  the 
  sea. 
  This 
  assemblage 
  of 
  pyrogenic 
  

   rocks, 
  rich 
  in 
  aluminous 
  silicates, 
  decomposes 
  under 
  the 
  chemical 
  action 
  

   of 
  the 
  water, 
  and 
  gives 
  rise 
  in 
  the 
  same 
  way 
  as 
  do 
  terrestrial 
  volcanic 
  

   rocks 
  to 
  argillaceous 
  matters, 
  according 
  to 
  reactions 
  we 
  can 
  always 
  

   observe 
  on 
  the 
  surface 
  of 
  the 
  globe, 
  and 
  which 
  are 
  too 
  well 
  known 
  

   to 
  need 
  special 
  mention 
  here. 
  t 
  

  

  The 
  detailed 
  microscopic 
  examination 
  of 
  hundreds 
  of 
  soundings 
  has 
  

   shown 
  that 
  we 
  can 
  always 
  demonstrate 
  in 
  the 
  argillaceous 
  matter 
  the 
  

   presence 
  of 
  pumice, 
  of 
  lapilli, 
  of 
  silicates, 
  and 
  other 
  volcanic 
  minerals 
  

   in 
  various 
  stages 
  of 
  decomposition. 
  

  

  As 
  we 
  have 
  shown 
  in 
  another 
  paper,* 
  the 
  deposit 
  most 
  widely 
  dis- 
  

   tributed 
  over 
  the 
  bed 
  of 
  modern 
  seas 
  is 
  due 
  to 
  the 
  decomposition 
  of 
  

   the 
  products 
  of 
  the 
  internal 
  activity 
  of 
  the 
  globe; 
  and 
  the 
  fiual 
  result 
  

   of 
  the 
  chemical 
  action 
  of 
  sea 
  water 
  is 
  seen 
  in 
  the 
  formation 
  of 
  this 
  

   argillaceous 
  matter, 
  which 
  is 
  found 
  everywhere 
  in 
  deep-sea 
  deposits, 
  

   sometimes 
  concealed 
  by 
  the 
  abundance 
  of 
  siliceous 
  or 
  calcareous 
  organ- 
  

   isms, 
  sometimes 
  appearing 
  with 
  its 
  own 
  proper 
  characteristics 
  asso- 
  

   ciated 
  with 
  mineral 
  substances, 
  some 
  of 
  which 
  allow 
  us 
  to 
  appreciate 
  

   the 
  extreme 
  slowness 
  of 
  its 
  formation, 
  or 
  whose 
  presence 
  corroborates 
  

   the 
  theory 
  advanced 
  to 
  exjdain 
  its 
  origin. 
  

  

  In 
  the 
  places 
  where 
  this 
  red 
  clay 
  attains 
  its 
  most 
  typical 
  development 
  

   we 
  may 
  follow, 
  step 
  by 
  step, 
  the 
  transformation 
  of 
  the 
  volcauic 
  frag- 
  

   ments 
  into 
  argillaceous 
  matter. 
  It 
  may 
  be 
  said 
  to 
  be 
  the 
  direct 
  prod- 
  

   uct 
  of 
  the 
  decomposition 
  of 
  the 
  basic 
  rocks, 
  represented 
  by 
  volcanic 
  

   glasses, 
  such 
  as 
  hyalomelan 
  and 
  tachylite. 
  This 
  decomposition, 
  in 
  spite 
  

   of 
  the 
  temperature 
  approximating 
  to 
  zero 
  (32° 
  F.), 
  gives 
  rise, 
  as 
  an 
  ul- 
  

   timate 
  product, 
  to 
  clearly 
  crystallized 
  minerals, 
  which 
  may 
  bo 
  consid- 
  

   ered 
  the 
  most 
  remarkable 
  products 
  of 
  the 
  chemical 
  action 
  of 
  the 
  sea 
  

   upon 
  the 
  volcanic 
  matters 
  undergoing 
  decomposition. 
  These 
  micro- 
  

   scopic 
  crystals 
  are 
  zeolites 
  lying 
  free 
  in 
  the 
  deposit, 
  and 
  are 
  met 
  with 
  

   in 
  greatest 
  abundance 
  in 
  the 
  typical 
  red-clay 
  areas 
  of 
  the 
  Central 
  Pacific. 
  

   They 
  are 
  simple, 
  twinned, 
  or 
  spheroidal 
  groups, 
  which 
  scarcely 
  exceed 
  

   half 
  a 
  millimeter 
  in 
  diameter. 
  The 
  crystallographic 
  and 
  chemical 
  study 
  

   of 
  them 
  shows 
  that 
  they 
  must 
  be 
  referred 
  to 
  christianite. 
  It 
  is 
  known 
  

   how 
  easily 
  the 
  zeolites 
  crystallize 
  in 
  the 
  pores 
  of 
  eruptive 
  rocks 
  in 
  pro- 
  

   cess 
  of 
  decomposition 
  ; 
  and 
  the 
  crystals 
  of 
  christianite, 
  which 
  we 
  ob- 
  

  

  " 
  On 
  Cosmic 
  and 
  Volcanic 
  Dust," 
  Proc. 
  Roy. 
  Soc. 
  Edin., 
  1883-'84. 
  

  

  