﻿142 
  II 
  K 
  Gregory— 
  La 
  Paz 
  (Bolivia) 
  Gorge. 
  

  

  depressions. 
  No 
  hills 
  rise 
  above 
  the 
  gravel-strewn 
  floor 
  which 
  

   appears 
  to 
  extend 
  as 
  an 
  unbroken 
  surface 
  to 
  the 
  foot 
  of 
  majes- 
  

   tic 
  Illampu. 
  At 
  Alto 
  a 
  surprise 
  awaits 
  the 
  traveler, 
  for 
  here, 
  

   without 
  preliminary 
  warning 
  in 
  change 
  of 
  slopes 
  or 
  eastward- 
  

   flowing 
  streams, 
  one 
  finds 
  himself 
  on 
  the 
  brink 
  of 
  a 
  canyon 
  

   cut 
  entirely 
  in 
  alluvial 
  deposits 
  to 
  a 
  depth 
  of 
  over 
  1500 
  feet. 
  

   At 
  the 
  foot 
  of 
  the 
  canyon 
  wall 
  lies 
  the 
  city 
  of 
  La 
  Paz, 
  whose 
  

   red 
  tile 
  roofs, 
  cathedral 
  spires 
  and 
  threads 
  of 
  streets, 
  broken 
  

   by 
  parks 
  and 
  traversed 
  by 
  streams 
  and 
  irrigation 
  ditches 
  com- 
  

   pose 
  a 
  unique 
  picture 
  of 
  singular 
  beauty. 
  

  

  Fig. 
  2. 
  

  

  ^n^E 
  

  

  

  

  

  v 
  xfe°P- 
  

  

  

  ■s'^-^ 
  

  

  ' 
  :: 
  >a.-j//. 
  

  

  ^ 
  

  

  IS: 
  

  

  w 
  

  

  

  1 
  "l-^v-***-? 
  

  

  • 
  y 
  

  

  ^J 
  

  

  a, 
  gravel, 
  sand. 
  £>, 
  tuff, 
  c, 
  sands, 
  gravel, 
  clay, 
  d, 
  lignite, 
  e, 
  sands, 
  gravel, 
  clay. 
  

   Fig. 
  2. 
  Generalized 
  section 
  of 
  La 
  Paz 
  gorge, 
  not 
  drawn 
  to 
  scale. 
  

  

  As 
  shown 
  in 
  the 
  view 
  (fig. 
  1), 
  looking 
  from 
  Alto 
  station 
  

   across 
  the 
  La 
  Paz 
  valley, 
  the 
  landscape 
  gives 
  no 
  suggestion 
  of 
  

   the 
  presence 
  of 
  such 
  a 
  chasm 
  and 
  one 
  is 
  reminded 
  forcibly 
  of 
  

   the 
  Colorado 
  Plateau 
  of 
  Arizona, 
  where 
  impassable 
  canyons 
  

   of 
  great 
  depth 
  are 
  revealed 
  only 
  when 
  one 
  is 
  standing 
  on 
  their 
  

   rim. 
  On 
  descending 
  the 
  canyon 
  walls 
  it 
  is 
  found 
  that 
  the 
  

   floor 
  is 
  by 
  no 
  means 
  flat, 
  but 
  is 
  cut 
  by 
  streams 
  which 
  flow 
  in 
  

   gorges 
  one 
  hundred 
  feet 
  and 
  more 
  in 
  depth, 
  between 
  and 
  over 
  

   which, 
  resting 
  on 
  hills 
  and 
  terraces, 
  the 
  city 
  is 
  built. 
  The 
  

   larger 
  part 
  of 
  the 
  buildings 
  are 
  distributed 
  along 
  two 
  more 
  or 
  

   less 
  dissected 
  terraces 
  whose 
  position 
  with 
  respect 
  to 
  the 
  

   valley 
  walls 
  is 
  shown 
  diagram 
  matically 
  in 
  fig. 
  2. 
  

  

  Between 
  San 
  Jorge 
  and 
  Obrajes 
  the 
  La 
  Paz 
  river 
  has 
  sunk 
  

   its 
  bed 
  into 
  sands 
  and 
  clays 
  whose 
  eroded 
  strata 
  exhibit 
  minia- 
  

   ture 
  " 
  bad 
  land 
  " 
  forms. 
  Lying 
  unconformably 
  above 
  these 
  

   finer 
  deposits 
  at 
  San 
  Jorge 
  and 
  northward 
  through 
  the 
  city 
  

   are 
  deposits 
  of 
  gravel 
  which 
  stand 
  as 
  nearly 
  vertical 
  walls 
  fifty 
  

   to 
  one 
  hundred 
  and 
  fifty 
  feet 
  high. 
  The 
  material 
  is 
  exces- 
  

   sively 
  coarse 
  and 
  contains 
  bowlders 
  of 
  white 
  granite 
  six 
  inches 
  

   to 
  six 
  feet 
  in 
  diameter. 
  Above 
  the 
  gravel 
  terraces, 
  forming 
  

   the 
  knobs 
  and 
  benches 
  and 
  ridges 
  of 
  the 
  western 
  part 
  of 
  the 
  

  

  