﻿192 
  H. 
  E. 
  Gregory 
  — 
  Geologic 
  Sketch 
  of 
  

  

  inland. 
  Agassiz 
  states'* 
  that 
  Lake 
  Arapa 
  and 
  several 
  lakes 
  

   near 
  the 
  west 
  shore 
  are 
  outliers 
  of 
  an 
  ancient 
  water 
  body, 
  and 
  

   that 
  the 
  plain 
  north 
  of 
  Lam 
  pa 
  "only 
  100-150 
  feet 
  above 
  the 
  

   lake 
  . 
  . 
  . 
  was 
  one 
  sheet 
  of 
  water." 
  "The 
  terraces 
  of 
  the 
  

   former 
  shores 
  are 
  still 
  very 
  distinctly 
  seen." 
  Tovar 
  also 
  

   records 
  the 
  tradition 
  that 
  Lake 
  Umayo, 
  now 
  fifteen 
  miles 
  

   distant 
  and 
  fifty 
  feet 
  more 
  or 
  less 
  above 
  the 
  Titicaca 
  level, 
  was 
  

   formerly 
  part 
  of 
  Titicaca 
  and 
  that 
  the 
  plains 
  about 
  the 
  north- 
  

   west 
  end 
  of 
  the 
  lake 
  were 
  formerly 
  less 
  extensive. 
  Yiscarraf 
  

   states 
  that 
  within 
  historical 
  times 
  the 
  peninsula 
  of 
  Copacabana 
  

   was 
  an 
  island. 
  La 
  Puente,^: 
  Zundt,§ 
  Posnansky,|| 
  Markham,^ 
  

   and 
  Conway** 
  accept 
  the 
  general 
  view 
  first 
  stated 
  by 
  Orton,ff 
  

   that 
  the 
  waters 
  of 
  the 
  lake 
  were 
  vastly 
  more 
  extensive 
  and 
  sur- 
  

   rounded 
  Tiahuanaco 
  within 
  historical 
  times. 
  J 
  t 
  

  

  When 
  the 
  Titicaca 
  coast 
  is 
  examined 
  it 
  appears 
  that 
  the 
  data 
  

   presented 
  by 
  Tovar 
  have 
  little 
  significance. 
  Most 
  of 
  the 
  places 
  

   mentioned 
  adjoin 
  very 
  shallow 
  waters 
  which 
  are 
  gradually 
  being 
  

   reclaimed 
  by 
  stream-borne 
  sediments 
  (fig. 
  3). 
  This 
  is 
  particu- 
  

   larly 
  true 
  of 
  the 
  areas 
  mentioned 
  by 
  Agassiz, 
  in 
  which 
  the 
  

   Lampa 
  and 
  Kames 
  are 
  aggrading 
  their 
  beds 
  and 
  carrying 
  sedi- 
  

   ment 
  forward 
  to 
  form 
  deltas. 
  Squier 
  appreciated 
  this 
  fact 
  and 
  

   remarks 
  that 
  " 
  the 
  region 
  around 
  the 
  mouth 
  of 
  the 
  Rames 
  is 
  a 
  

   kind 
  of 
  delta, 
  very 
  low 
  and 
  level, 
  interspersed 
  with 
  shallow 
  

   pools 
  as 
  if 
  but 
  recently 
  half 
  rescued 
  from 
  the 
  lake 
  by 
  deposits 
  

   from 
  the 
  river.'- 
  That 
  the 
  lake 
  level 
  has 
  been 
  eight 
  to 
  twelve 
  

   feet 
  higher 
  than 
  to-day 
  is 
  shown' 
  by 
  the 
  whitish 
  band 
  of 
  

   deposited 
  salts 
  and 
  discolored 
  rock 
  which 
  decorates 
  the 
  bases 
  

   of 
  rock 
  islands. 
  While 
  in 
  part 
  the 
  evidence 
  of 
  the 
  height 
  

   reached 
  by 
  breakers, 
  this 
  horizontal 
  band 
  strongly 
  suggests 
  a 
  

   former 
  level 
  below 
  which 
  the 
  waters 
  have 
  sunk 
  within 
  prob- 
  

   ably 
  a 
  few 
  decades. 
  The 
  annual 
  fluctuation 
  in 
  lake 
  level 
  is 
  

   approximately 
  4 
  feet, 
  and 
  so 
  shallow 
  is 
  the 
  bottom 
  in 
  places 
  

   that 
  hogs 
  may 
  feed 
  several 
  hundred 
  feet 
  from 
  shore. 
  In 
  the 
  

   absence 
  of 
  quantitative 
  measurements 
  and 
  of 
  definite 
  locations 
  

   of 
  ancient 
  shore 
  lines, 
  the 
  conclusion 
  of 
  Tovar 
  that 
  the 
  lake 
  is 
  

   " 
  regularly 
  diminishing 
  " 
  in 
  a 
  " 
  surprising 
  manner 
  " 
  is 
  not 
  

   justified. 
  

  

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

  

  f 
  Copacabana 
  de 
  loslncas, 
  La 
  Paz, 
  1901. 
  

  

  % 
  Bol. 
  Soc. 
  Geog. 
  de 
  Lima. 
  Tomo 
  I, 
  1892. 
  

  

  § 
  Op. 
  cit. 
  

  

  || 
  Bol. 
  oficina 
  Nacional 
  de 
  Estadistica 
  de 
  Bolivia, 
  1911. 
  

  

  If 
  Geog. 
  Jour., 
  October, 
  1910. 
  

  

  ** 
  Climbing 
  and 
  Explorations 
  in 
  the 
  Bolivian 
  Andes, 
  1901. 
  

  

  ft 
  The 
  Andes 
  and 
  the 
  Amazon, 
  1876. 
  

  

  XX 
  In 
  a 
  paper 
  presented 
  by 
  Professor 
  Bowman 
  before 
  the 
  Association 
  of 
  

   American 
  Geographers, 
  December, 
  1912, 
  and 
  later 
  to 
  be 
  published, 
  the 
  role 
  

   played 
  by 
  Lake 
  Titicaca 
  in 
  the 
  history 
  of 
  ancient 
  Tiahuanaco 
  is 
  discussed 
  in 
  

   detail. 
  

  

  