﻿Titicaca 
  Island 
  and 
  Adjoining 
  Areas. 
  189 
  

  

  the 
  tributary 
  streams, 
  and 
  how 
  much 
  to 
  original 
  depression, 
  is 
  

   impossible 
  to 
  determine, 
  but 
  it 
  is 
  significant 
  that 
  bays 
  of 
  great 
  

   depths 
  and 
  precipitous 
  shore 
  fronts 
  as 
  Yampupata, 
  Tiquina, 
  

   Huaicho, 
  Conina, 
  and 
  Huancane 
  do 
  not 
  furnish 
  an 
  outlet 
  for 
  

   debris-laden 
  streams 
  of 
  large 
  size. 
  Soundings 
  so 
  far 
  avail- 
  

   able 
  fail 
  to 
  indicate 
  under-water 
  channels 
  or 
  canyons 
  whose 
  

   orientation 
  may 
  be 
  determined. 
  That 
  the 
  basin, 
  somewhat 
  

   extended, 
  is 
  a 
  warped, 
  downfaultecl 
  area, 
  is 
  suggested 
  by 
  the 
  

  

  Fig. 
  2. 
  

  

  o 
  

  

  i 
  § 
  

  

  og 
  Titicaca 
  ^ 
  

  

  g 
  Island 
  

  

  Fig. 
  2. 
  Section 
  across 
  Lake 
  Titicaca 
  from 
  Carabuca 
  to 
  Pomata 
  showing 
  

   mountainous 
  character 
  of 
  Titicaca 
  Island. 
  

  

  rectilinear 
  quality 
  of 
  shore 
  and 
  island 
  borders. 
  It 
  would 
  appear 
  

   also, 
  from 
  the 
  character 
  of 
  the 
  under-water 
  slopes, 
  that 
  the 
  

   topography 
  had 
  reached 
  a 
  stage 
  of 
  early 
  maturity 
  before 
  the 
  

   advent 
  of 
  structural 
  movements 
  which 
  prepared 
  the 
  basin 
  for 
  

   filling 
  by 
  water. 
  

  

  The 
  floor 
  of 
  the 
  lake 
  basin, 
  in 
  its 
  deepest 
  part 
  and 
  frequently 
  

   near 
  shore, 
  was 
  found 
  by 
  Agassiz* 
  to 
  be 
  covered 
  with 
  k 
  ' 
  thick 
  

   mud, 
  the 
  finest 
  possible 
  greenish 
  black 
  silt 
  containing 
  few 
  frag- 
  

   ments 
  of 
  shells 
  — 
  the 
  mass 
  being 
  probably 
  several 
  feet 
  thick." 
  

   In 
  a 
  few 
  localities 
  sandy, 
  shelly, 
  and 
  rocky 
  bottom 
  was 
  found. 
  

   The 
  bed 
  of 
  Lago 
  Pequeno 
  appears 
  to 
  be 
  covered 
  with 
  sand. 
  

   Professor 
  Thoulet 
  analyzed 
  three 
  samples 
  obtained 
  by 
  LeMaire, 
  

   the 
  first 
  from 
  Lago 
  Pequeno 
  near 
  shore 
  at 
  Chillilaya, 
  the 
  

   second 
  from 
  a 
  depth 
  of 
  741 
  feet, 
  the 
  third 
  from 
  near 
  shore 
  at 
  

   Huaicho 
  on 
  Lago 
  Grande. 
  The 
  gray 
  slime 
  from 
  Chillilaya 
  

   contained 
  microscopic 
  fragments 
  of 
  siliceous 
  spicules 
  and 
  dia- 
  

   toms, 
  black, 
  ferruginous, 
  combustible 
  specks 
  (coal?), 
  brick- 
  

   colored 
  particles, 
  minute 
  angular 
  quartzes, 
  black 
  magnetic 
  

   grains 
  and 
  sparsely 
  distributed 
  obsidian, 
  pumice, 
  hornblende, 
  

   olivine, 
  pyroxene, 
  and 
  mica. 
  Percentage 
  calculations 
  of 
  these 
  

   samples 
  gave 
  : 
  sand 
  and 
  plant 
  fragments 
  13 
  ; 
  calcareous 
  slime 
  3 
  ; 
  

   non-calcareous 
  slime 
  13 
  ; 
  calcareous 
  mud 
  59 
  ; 
  organic 
  residue 
  

   12. 
  Both 
  entire 
  and 
  fragmentary 
  shells 
  were 
  recovered. 
  The 
  

   sample 
  from 
  deep 
  water 
  gave 
  in 
  parts 
  per 
  100 
  : 
  sand, 
  etc. 
  3 
  ; 
  

   * 
  Proc. 
  Am. 
  Acad., 
  vol. 
  xi, 
  p. 
  284, 
  1875-76. 
  

  

  