﻿656 
  SOUTH 
  AMERICAN 
  INDIANS 
  [B. 
  A. 
  E. 
  Bull. 
  143 
  

  

  Frengueli 
  (1940) 
  has 
  carefully 
  studied 
  the 
  geomorphological 
  nature 
  of 
  

   this 
  terrain. 
  

  

  The 
  principal 
  human 
  settlements 
  were 
  near 
  permanent 
  sources 
  of 
  

   water. 
  Scarcity 
  of 
  water 
  forced 
  routes 
  of 
  travel 
  to 
  follow 
  the 
  rivers 
  

   and 
  the 
  adjoining 
  marshes. 
  Of 
  the 
  two 
  rivers, 
  the 
  Kio 
  Dulce 
  (Sweet 
  

   River) 
  was 
  preferred, 
  for, 
  as 
  its 
  name 
  implies, 
  it 
  has 
  a 
  good 
  supply 
  of 
  

   crystal-clear 
  water 
  from 
  the 
  eastern 
  slopes 
  of 
  the 
  Aconquij 
  a 
  Mountains. 
  

   The 
  Rio 
  Salado 
  (Salty 
  River), 
  although 
  having 
  a 
  small 
  salt 
  content, 
  

   extremely 
  low 
  water, 
  and 
  frequent 
  interruptions, 
  was 
  useful 
  because 
  

   its 
  great 
  length 
  (more 
  than 
  2,000 
  km., 
  about 
  1,250 
  miles) 
  facilitated 
  

   communication 
  between 
  important 
  zones, 
  from 
  the 
  distant 
  puna 
  to 
  

   the 
  Rio 
  Parand, 
  whence 
  drains 
  an 
  enormous 
  river 
  basin. 
  

  

  At 
  short 
  intervals 
  along 
  the 
  left 
  bank 
  of 
  the 
  principal 
  course 
  of 
  the 
  

   Rio 
  Salado 
  are 
  several 
  thousand 
  mounds, 
  each 
  1 
  or 
  2 
  m. 
  (about 
  3 
  to 
  6 
  

   ft.) 
  high, 
  which 
  form 
  an 
  irregular 
  and 
  almost 
  continuous 
  band, 
  usually 
  

   about 
  1 
  to 
  3 
  km. 
  (about 
  2/3 
  to 
  2 
  miles) 
  wide. 
  These 
  mounds 
  are 
  

   irregularly 
  elliptic, 
  the 
  longer 
  axis 
  oriented 
  in 
  the 
  direction 
  of 
  the 
  

   nearby 
  beds 
  or 
  depressions. 
  Their 
  surface 
  areas 
  vary 
  from 
  ten 
  to 
  

   hundreds 
  of 
  square 
  meters. 
  In 
  Merced 
  de 
  Tacana, 
  Frengueli 
  (1940) 
  

   measured 
  mounds 
  32 
  and 
  53 
  meters 
  (about 
  100 
  and 
  170 
  ft.) 
  long, 
  

   respectively. 
  Their 
  composition 
  and 
  structure 
  are 
  variable, 
  and 
  they 
  

   can 
  be 
  classified 
  as 
  sandy, 
  marshy, 
  marshy-loess. 
  All 
  have 
  two 
  

   features 
  in 
  common: 
  a 
  base 
  of 
  very 
  fine, 
  compact 
  dark 
  to 
  gray, 
  some- 
  

   what 
  micaceous 
  silt 
  which 
  is 
  generally 
  cracked 
  into 
  clods 
  newly 
  solidi- 
  

   fied 
  by 
  infiltrations; 
  and 
  an 
  upper 
  layer 
  which 
  is 
  aeolian 
  (wind-borne) 
  

   soil, 
  a 
  true 
  loess 
  formation. 
  It 
  is 
  a 
  friable 
  darkish-gray 
  earth 
  which 
  is 
  

   easily 
  reduced 
  to 
  dust 
  and 
  is 
  held 
  together 
  by 
  very 
  small 
  roots. 
  In 
  

   the 
  sandy 
  mounds, 
  the 
  soil 
  gets 
  thinner 
  and 
  sometimes 
  is 
  mixed 
  with 
  

   the 
  surface 
  sand. 
  In 
  the 
  depressions, 
  it 
  is 
  almost 
  transformed 
  into 
  

   slime 
  but 
  everywhere 
  it 
  is 
  almost 
  a 
  continuous 
  covering, 
  15 
  to 
  60 
  cm. 
  

   (6 
  to 
  24 
  inches) 
  thick. 
  What 
  differentiates 
  the 
  mounds 
  is 
  the 
  material. 
  

   The 
  sandy 
  mounds 
  consist 
  exclusively 
  of 
  fine-grained, 
  wind-borne 
  

   sand, 
  with 
  a 
  small 
  admixture 
  of 
  loess. 
  The 
  marshy 
  mounds 
  are 
  com- 
  

   posed 
  of 
  a 
  porous, 
  greenish-gray 
  slime 
  with 
  dark 
  streaks. 
  The 
  earth, 
  

   sometimes 
  light 
  and 
  spongy, 
  is 
  irregularly 
  stratified 
  into 
  layers 
  and 
  

   small, 
  extremely 
  thin 
  laminae, 
  1 
  to 
  2 
  cm. 
  (% 
  to 
  % 
  in.) 
  thick. 
  The 
  

   marshy-loess 
  mounds 
  consist 
  of 
  two 
  principal 
  layers: 
  a 
  lower 
  layer 
  of 
  

   dark-grayish 
  dusty 
  loess 
  and 
  an 
  upper 
  layer 
  of 
  medium 
  dark, 
  very 
  

   porous, 
  friable 
  loess. 
  These 
  three 
  types 
  of 
  mounds 
  occur 
  in 
  different 
  

   zones, 
  but 
  all 
  are 
  unquestionably 
  natural 
  formations. 
  They 
  cannot 
  

   be 
  interpreted 
  as 
  tumuli, 
  that 
  is, 
  as 
  artificial 
  formations 
  built 
  by 
  the 
  

   ancient 
  inhabitants. 
  These 
  conclusions, 
  drawn 
  from 
  the 
  geomorpho- 
  

   logical 
  examination 
  of 
  the 
  mounds, 
  are 
  of 
  extraordinary 
  importance, 
  

   as 
  we 
  shall 
  see, 
  to 
  the 
  analysis 
  of 
  the 
  archeological 
  problem 
  of 
  the 
  

   Chaco 
  Santiagueno. 
  

  

  