﻿188 
  II. 
  E. 
  Gregory 
  — 
  Geologic 
  Sketch 
  of 
  

  

  lake 
  (Lago 
  Pequeno) 
  is 
  shallow, 
  with 
  gently 
  sloping 
  "bottom 
  

   flats 
  and 
  large 
  areas 
  of 
  low 
  shore 
  from 
  which 
  rise 
  rock 
  knobs 
  

   and 
  hogbacks 
  of 
  moderate 
  height. 
  The 
  main 
  lake 
  (Lago 
  

   Grande) 
  reaches 
  a 
  depth 
  of 
  over 
  nine 
  hundred 
  feet 
  and 
  is 
  

   bordered 
  by 
  abruptly 
  descending 
  under-water 
  shelves. 
  Twenty- 
  

   live 
  tributaries, 
  all 
  small 
  and 
  greatly 
  fluctuating 
  in 
  response 
  to 
  

   seasonal 
  precipitation, 
  supply 
  the 
  lake. 
  Its 
  surplus 
  waters 
  are 
  

   carried 
  by 
  the 
  Desaguadero 
  into 
  the 
  salt 
  Lake 
  Poopo, 
  thus 
  

   forming 
  a 
  chain 
  of 
  fresh- 
  and 
  salt-water 
  bodies 
  like 
  the 
  Sea 
  of 
  

   Galilee-Jordan 
  River-Dead 
  Sea 
  of 
  Palestine 
  and 
  Utah 
  Lake- 
  

   Jordan 
  Kiver-Great 
  Salt 
  Lake 
  of 
  Utah. 
  Thirty-six 
  islands 
  

   rise 
  above 
  the 
  surface. 
  The 
  largest 
  of 
  these, 
  Titicaca, 
  has 
  

   given 
  its 
  name 
  to 
  the 
  lake, 
  and 
  as 
  the 
  Island 
  of 
  the 
  Sun, 
  shares 
  

   with 
  Koati 
  (the 
  Island 
  of 
  the 
  Moon) 
  and 
  Tiahuanaco, 
  a 
  posi- 
  

   tion 
  as 
  a 
  center 
  for 
  archaeological 
  and 
  historical 
  research. 
  

  

  Ph 
  ys 
  iography. 
  

  

  The 
  Lake 
  Floor. 
  — 
  The 
  soundings 
  made 
  by 
  LeMaire* 
  and 
  by 
  

   Agassiz,f 
  supplemented 
  by 
  scattered 
  data, 
  are 
  sufficient 
  for 
  the 
  

   construction 
  of 
  a 
  bathymetric 
  map 
  of 
  the 
  basin 
  now 
  occupied 
  

   by 
  the 
  waters 
  of 
  Titicaca. 
  (See 
  fig. 
  1, 
  Plate 
  I.) 
  

  

  It 
  will 
  be 
  noted 
  that 
  Lago 
  Pequeno 
  is, 
  properly 
  speaking, 
  not 
  

   a 
  part 
  of 
  the 
  depression 
  holding 
  the 
  waters 
  of 
  Titicaca. 
  Its 
  

   floor 
  is 
  remarkably 
  flat, 
  less 
  than 
  one-tenth 
  of 
  its 
  area 
  reaching 
  

   a 
  depth 
  exceeding 
  20 
  feet 
  ; 
  and 
  a 
  fall 
  of 
  ten 
  feet 
  in 
  water 
  level 
  

   would 
  expose 
  about 
  one-fifth 
  of 
  its 
  bed, 
  and 
  effectively 
  impede 
  

   navigation. 
  Lago 
  Grande 
  is 
  seen 
  to 
  occupy 
  a 
  rectangular 
  

   basin 
  with 
  abruptly 
  ascending 
  edges 
  on 
  three 
  sides, 
  and 
  with 
  a 
  

   slope 
  from 
  southwest 
  to 
  northeast. 
  The 
  southeastern 
  extrem- 
  

   ity 
  partakes 
  of 
  the 
  nature 
  of 
  a 
  canyon, 
  — 
  Tiquina 
  is 
  a 
  sharp-cut 
  

   valley 
  included 
  between 
  steeply 
  sloping 
  rock 
  walls. 
  The 
  islands 
  

   of 
  Titicaca 
  (fig. 
  2), 
  Koati, 
  and 
  Soto 
  are 
  mountains, 
  rising 
  respec- 
  

   tively 
  1,400, 
  1,500, 
  and 
  1,300 
  feet 
  above 
  the 
  basin 
  floor, 
  while 
  the 
  

   archipelago 
  facing 
  the 
  coast 
  at 
  Escoma 
  includes 
  stacks 
  and 
  pin- 
  

   nacles, 
  erosion 
  remnants, 
  rising 
  above 
  a 
  slightly 
  submerged 
  

   platform. 
  There 
  are 
  no 
  indications 
  that 
  the 
  tiny 
  islands 
  adjoin- 
  

   ing 
  Titicaca 
  Island 
  form 
  steps 
  in 
  a 
  submerged 
  causeway 
  unit- 
  

   ing 
  Copacabana 
  with 
  the 
  Bolivian 
  mainland 
  at 
  Huaicho, 
  as 
  

   surmised 
  by 
  Bandelier, 
  and 
  no 
  proof 
  that 
  the 
  straits 
  of 
  Tiquina 
  

   have 
  been 
  opened 
  by 
  faulting 
  or 
  torrent 
  erosion 
  since 
  the 
  lake 
  

   attained 
  its 
  present 
  dimensions, 
  as 
  is 
  implied 
  by 
  various 
  writers. 
  

   How 
  much 
  of 
  the 
  shallowness 
  of 
  the 
  bays 
  of 
  Puno, 
  Rames 
  and 
  

   Achacache 
  and 
  of 
  Lago 
  Pequeno 
  is 
  due 
  to 
  waste 
  furnished 
  by 
  

  

  * 
  Les 
  Lacs 
  des 
  Hants 
  Plateaux 
  de 
  L'Amevique 
  du 
  snd, 
  Paris, 
  1906. 
  

   t 
  Hydrographic 
  sketch 
  of 
  Lake 
  Titicaca, 
  Proc. 
  Am. 
  Acad. 
  Arts 
  and 
  Sci., 
  

   vol. 
  xi, 
  1875-76. 
  

  

  