﻿776 
  REPORT 
  OF 
  COMMISSIONER 
  OP 
  FISH 
  AND 
  FISHERIES. 
  [18] 
  

  

  blue 
  muds. 
  The 
  green 
  muds 
  and 
  sands 
  occupy, 
  as 
  a 
  rule, 
  portions 
  of 
  

   the 
  coast 
  where 
  cletrital 
  matter 
  from 
  rivers 
  is 
  not, 
  apparently, 
  accumu- 
  

   lating 
  at 
  a 
  rapid 
  rate, 
  viz, 
  on 
  such 
  places 
  as 
  the 
  Angulhas 
  Bank, 
  off 
  the 
  

   east 
  coast 
  of 
  Australia, 
  off 
  the 
  coast 
  of 
  Spain, 
  and 
  at 
  various 
  points 
  

   along 
  the 
  coast 
  of 
  America. 
  

  

  Let 
  us 
  cast 
  a 
  glance 
  at 
  the 
  region 
  occupied 
  by 
  terrigenous 
  deposits, 
  

   in 
  which 
  we 
  include 
  all 
  truly 
  littoral 
  formations. 
  This 
  region 
  extends 
  

   from 
  high- 
  water 
  mark 
  down, 
  it 
  may 
  be, 
  to 
  a 
  depth 
  of 
  over 
  4 
  miles, 
  and 
  

   in 
  a 
  horizontal 
  direction 
  from 
  60 
  to 
  perhaps 
  300 
  miles 
  seawards, 
  and 
  in- 
  

   cludes, 
  in 
  the 
  view 
  we 
  take, 
  all 
  inland 
  seas, 
  such 
  as 
  the 
  North 
  Sea, 
  Nor- 
  

   wegian 
  Sea, 
  Mediterranean 
  Sea, 
  Red 
  Sea, 
  China 
  Sea, 
  Japan 
  Sea, 
  Carib- 
  

   bean 
  Sea, 
  and 
  many 
  others. 
  It 
  is 
  the 
  region 
  of 
  change 
  and 
  of 
  variety 
  

   with 
  respect 
  to 
  light, 
  temperature, 
  motion, 
  and 
  biological 
  conditions. 
  

   In 
  the 
  surface 
  waters 
  the 
  temperature 
  ranges 
  from 
  80° 
  P. 
  in 
  the 
  tropics 
  

   to 
  28° 
  F. 
  in 
  the 
  polar 
  regions. 
  Below 
  the 
  surface 
  down 
  to 
  the 
  nearly 
  

   ice-cold 
  water 
  found 
  at 
  the 
  lower 
  limits 
  of 
  the 
  region 
  in 
  the 
  deep 
  sea 
  

   there 
  is 
  in 
  the 
  tropics 
  an 
  equally 
  great 
  range 
  of 
  temperature. 
  Plants 
  

   and 
  animals 
  are 
  abundant 
  near 
  the 
  shore, 
  and 
  animals 
  extend 
  in 
  rela- 
  

   tively 
  great 
  abundance 
  down 
  to 
  the 
  lower 
  limits 
  of 
  this 
  region, 
  which 
  is 
  

   now 
  covered 
  with 
  these 
  terrigenous 
  deposits. 
  The 
  specific 
  gravity 
  of 
  

   the 
  water 
  varies 
  much, 
  owiug 
  to 
  mixture 
  with 
  river 
  water 
  or 
  great 
  local 
  

   evaporation, 
  and 
  this 
  variation 
  in 
  its 
  turn 
  affects 
  the 
  fauna 
  and 
  flora. 
  In 
  

   the 
  terrigeuous 
  region 
  tides 
  and 
  currents 
  produce 
  their 
  maximum 
  ef- 
  

   fect, 
  and 
  these 
  influences 
  can 
  in 
  some 
  instances 
  be 
  traced 
  to 
  a 
  depth 
  of 
  

   300 
  fathoms, 
  or 
  nearly 
  2,000 
  feet. 
  The 
  upper 
  or 
  continental 
  margin 
  of 
  

   the 
  region 
  is 
  clearly 
  defined 
  by 
  the 
  high-water 
  mark 
  of 
  the 
  coast-line, 
  

   which 
  is 
  constantly 
  changing 
  through 
  breaker 
  action, 
  elevation, 
  and 
  

   subsidence. 
  The 
  lower 
  or 
  abysmal 
  margin 
  is 
  less 
  clearly 
  marked 
  out. 
  

   It 
  passes 
  in 
  most 
  cases 
  insensibly 
  into 
  the 
  abysmal 
  region, 
  but 
  may 
  be 
  

   regarded 
  as 
  ending 
  when 
  the 
  mineral 
  particles 
  from 
  the 
  neighboring 
  

   continents 
  begin 
  to 
  disappear 
  from 
  the 
  deposits, 
  which 
  then 
  pass 
  into 
  

   an 
  organic 
  ooze 
  or 
  a 
  red 
  clay. 
  

  

  Contrast 
  with 
  these 
  those 
  conditions 
  which 
  prevail 
  in 
  the 
  abysmal 
  

   region 
  in 
  which 
  occur 
  the 
  organic 
  oozes 
  and 
  red 
  clay, 
  the 
  distribution 
  of 
  

   which 
  will 
  presently 
  be 
  considered. 
  This 
  area 
  comprises 
  vast 
  undulating 
  

   plains 
  from 
  2 
  to 
  5 
  miles 
  beneath 
  the 
  surface 
  of 
  the 
  sea, 
  the 
  average 
  be- 
  

   ing 
  about 
  3 
  miles, 
  here 
  and 
  there 
  interrupted 
  by 
  huge 
  volcanic 
  cones 
  

   (the 
  oceanic 
  islands). 
  No 
  sunlight 
  ever 
  reaches 
  these 
  deep, 
  cold 
  tracts. 
  

   The 
  range 
  of 
  temperature 
  over 
  them 
  is 
  not 
  more 
  than 
  7°, 
  viz, 
  from 
  31° 
  

   to 
  38° 
  F., 
  and 
  is 
  apparently 
  constant 
  throughout 
  the 
  whole 
  year 
  in 
  each 
  

   locality. 
  Plant 
  life 
  is 
  absent, 
  and, 
  although 
  animals 
  belonging 
  to 
  all 
  

   the 
  great 
  types 
  are 
  present, 
  there 
  is 
  no 
  great 
  variety 
  of 
  form 
  or 
  abun- 
  

   dance 
  of 
  individuals. 
  Change 
  of 
  any 
  kind 
  is 
  exceedingly 
  slow. 
  

  

  What 
  is 
  the 
  distribution 
  of 
  deposits 
  in 
  this 
  abysmal 
  region 
  of 
  the 
  

   earth's 
  surface? 
  In 
  the 
  tropical 
  and 
  temperate 
  zones 
  of 
  the 
  great 
  

   oceans, 
  which 
  occupy 
  about 
  110° 
  of 
  latitude 
  between 
  the 
  two 
  polar 
  

  

  