﻿194 
  II. 
  E. 
  Gregory 
  — 
  Geologic 
  Sketch 
  of 
  

  

  of 
  the 
  lake. 
  Until 
  long-term, 
  continuous 
  records 
  are 
  available, 
  

   it 
  seems 
  best 
  to 
  assume 
  that 
  Titicaca, 
  in 
  common 
  with 
  other 
  

   water 
  bodies, 
  rises 
  and 
  falls 
  in 
  response 
  to 
  the 
  increased 
  and 
  

   decreased 
  precipitation 
  which 
  characterizes 
  climatic 
  cycles, 
  the 
  

   existence 
  of 
  which 
  has 
  been 
  demonstrated 
  for 
  other 
  parts 
  of 
  

   the 
  world. 
  The 
  hypothesis 
  of 
  progressive 
  diminution 
  through 
  

   centuries 
  of 
  time 
  would 
  accordingly 
  be 
  discarded. 
  

  

  Former 
  Extent. 
  — 
  That 
  Titicaca 
  is 
  the 
  diminished 
  represen- 
  

   tative 
  of 
  a 
  vast 
  interior 
  sea 
  which 
  covered 
  the 
  altiplano 
  in 
  

   northern 
  Bolivia 
  and 
  southern 
  Peru, 
  is 
  claimed 
  by 
  nearly 
  all 
  

   students 
  of 
  this 
  region. 
  Thus, 
  Agassiz 
  states,* 
  " 
  Lake 
  Titicaca 
  

   itself 
  must 
  have, 
  within 
  a 
  comparatively 
  very 
  recent 
  geological 
  

   period, 
  formed 
  quite 
  an 
  inland 
  sea. 
  The 
  terraces 
  of 
  its 
  former 
  

   shores 
  are 
  everywhere 
  most 
  distinctly 
  to 
  be 
  traced, 
  showing 
  

   that 
  its 
  water 
  level 
  must 
  have 
  had 
  an 
  elevation 
  of 
  300 
  or 
  400 
  

   feet 
  at 
  least 
  higher 
  than 
  its 
  present 
  level." 
  Le 
  Mairef 
  accepts 
  

   Agassiz's 
  conclusions, 
  supplemented 
  by 
  the 
  existence 
  of 
  an 
  

   ancient 
  beach 
  line 
  in 
  the 
  Poopo 
  basin, 
  first 
  observed 
  by 
  Mus- 
  

   ters,;); 
  and 
  concludes 
  that 
  Titicaca 
  and 
  Poopo 
  are 
  parts 
  of 
  one 
  

   interior 
  sea 
  covering 
  the 
  region 
  between 
  15° 
  and 
  21° 
  south 
  lat- 
  

   itude, 
  including 
  La 
  Paz 
  and 
  Oruro. 
  The 
  outlet 
  was 
  supposed 
  

   to 
  be 
  through 
  the 
  present 
  La 
  Paz 
  river 
  into 
  the 
  Atlantic. 
  

   "The 
  largest 
  lake 
  in 
  the 
  world 
  fed 
  the 
  largest 
  river 
  in 
  the 
  

   world." 
  " 
  Within 
  historical 
  times 
  the 
  Desaguadero 
  has 
  been 
  

   reduced 
  from 
  a 
  wide 
  strait 
  to 
  its 
  present 
  dimensions." 
  La 
  

   Puente§ 
  holds 
  the 
  same 
  view 
  but 
  mentions 
  no 
  evidence 
  

   bearing 
  on 
  this 
  point. 
  Posnansky! 
  believes 
  that 
  Titicaca 
  is 
  a 
  

   remnant 
  of 
  an 
  enormous 
  salt 
  sea 
  separated 
  from 
  the 
  ocean 
  by 
  

   uplift 
  and 
  drained 
  through 
  the 
  eastern 
  Cordilleras 
  by 
  a 
  passage 
  

   prepared 
  by 
  a 
  cataclysmic 
  rupture 
  of 
  its 
  barrier. 
  As 
  if 
  this 
  

   were 
  not 
  sufficient 
  proof 
  of 
  the 
  power 
  of 
  the 
  " 
  titanic 
  forces 
  of 
  

   nature," 
  Posnansky 
  states 
  that 
  the 
  region 
  was 
  again 
  flooded 
  by 
  

   waters 
  from 
  Lagunillos 
  freed 
  by 
  the 
  rupture 
  of 
  massive 
  rock 
  

   walls, 
  — 
  a 
  disaster 
  which 
  destroyed 
  the 
  civilization 
  represented 
  

   by 
  Tiahuanaco 
  ! 
  Zundt's 
  original 
  views^f 
  were 
  in 
  harmony 
  

   with 
  those 
  of 
  Posnansky 
  and 
  required 
  the 
  elevation 
  of 
  strata 
  

   to 
  a 
  height 
  of 
  13,000 
  feet 
  without 
  destroying 
  their 
  horizontal- 
  

   ity. 
  The 
  steep 
  faces 
  of 
  the 
  mesas 
  were 
  considered 
  the 
  work 
  of 
  

   waves. 
  Zundt's 
  later 
  interpretation** 
  is 
  based 
  on 
  the 
  hypoth- 
  

   esis 
  of 
  a 
  late 
  Tertiary 
  river, 
  " 
  Rio 
  Titicaca,"' 
  which 
  extended 
  

   from 
  Sicuani, 
  Peru, 
  to 
  Ulimani, 
  Bolivia, 
  via 
  La 
  Paz. 
  This 
  

  

  * 
  Proc. 
  Am. 
  Acad. 
  Arts 
  and 
  Sci., 
  vol. 
  xi, 
  1875-76, 
  p. 
  288. 
  

   f 
  Lagos 
  de 
  Los 
  Altiplanos, 
  pp. 
  153-154. 
  La 
  Paz, 
  1909. 
  

   JGeog. 
  Jour., 
  xlvi, 
  1871-77. 
  § 
  Op. 
  cit., 
  1892. 
  

  

  || 
  Bol. 
  officina 
  Nacional 
  de 
  Estadistica 
  de 
  Bolivia, 
  64-66, 
  Lh 
  Paz, 
  1911, 
  

   pp. 
  689-702. 
  

  

  % 
  Appendix, 
  D'Orbigny, 
  1907. 
  

  

  **Bol. 
  Estadistica, 
  67-69, 
  1911, 
  and 
  70-72, 
  1912. 
  

  

  