﻿II. 
  E. 
  Gregory 
  — 
  Gravels 
  at 
  Cuzco. 
  29 
  

  

  not 
  been 
  progressively 
  continuous, 
  is 
  shown 
  by 
  the 
  terraces 
  

   along 
  the 
  upper 
  Huatanay 
  (Sappi) 
  and 
  still 
  more 
  plainly 
  by 
  

   the 
  well-developed 
  terraces, 
  two 
  to 
  five 
  in 
  number, 
  flanking 
  

   the 
  streams 
  entering 
  the 
  Cuzco 
  valley 
  beyond 
  the 
  limits 
  of 
  the 
  

   fan. 
  No 
  well-marked 
  terraces 
  persist 
  in 
  the 
  upper 
  Ayahuaycco 
  

   Quebrada, 
  a 
  location 
  unfavorable 
  for 
  their 
  preservation. 
  The 
  

   canyon 
  is 
  narrow, 
  the 
  banks 
  are 
  of 
  gravel 
  or 
  of 
  gravel 
  on 
  rock, 
  

   and 
  the 
  stream 
  is 
  fed 
  by 
  wet-weather 
  torrential 
  tributaries 
  

   with 
  gradients 
  of 
  over 
  1500 
  feet 
  per 
  mile. 
  Here, 
  as 
  along 
  

   other 
  streams 
  entering 
  the 
  Cuzco 
  valley, 
  terraces 
  may 
  have 
  

   been 
  buried 
  and 
  re-excavated 
  many 
  times 
  in 
  response 
  to 
  minor 
  

   climatic 
  fluctuations 
  during 
  historic 
  as 
  well 
  as 
  prehistoric 
  

   times, 
  the 
  evidence 
  for 
  which 
  is 
  conclusive. 
  It 
  is 
  unprofitable, 
  

   from 
  a 
  geological 
  standpoint, 
  to 
  work 
  out 
  the 
  details 
  of 
  ero- 
  

   sional 
  history 
  in 
  and 
  about 
  Cuzco, 
  because 
  of 
  the 
  extensive 
  

   modification 
  of 
  slopes 
  and 
  terraces 
  resulting 
  from 
  cultivation 
  

   and 
  flood-water 
  irrigation. 
  However, 
  the 
  evidence 
  indicating 
  

   periodic 
  destruction 
  and 
  building 
  of 
  terraces, 
  even 
  within 
  the 
  

   past 
  one 
  hundred 
  years, 
  removes 
  the 
  necessity 
  of 
  ascribing 
  

   great 
  antiquity 
  to 
  animal 
  bones, 
  parts 
  of 
  human 
  skeletons, 
  and 
  

   fragments 
  of 
  pottery 
  found 
  along 
  stream 
  banks 
  and 
  which 
  may 
  

   have 
  been 
  deposited 
  on 
  terraces 
  or 
  on 
  banks, 
  or 
  in 
  the 
  numer- 
  

   ous 
  small 
  cave-like 
  openings 
  in 
  the 
  gravels, 
  to 
  be 
  transported, 
  

   buried, 
  or 
  reexposed 
  during 
  alternating 
  processes 
  of 
  deposition 
  

   and 
  degradation. 
  It 
  is 
  interesting 
  to 
  note 
  that 
  in 
  the 
  canyoned 
  

   tributaries 
  of 
  the 
  Sappi 
  and 
  of 
  streams 
  leading 
  from 
  the 
  lime- 
  

   stone 
  plateau 
  and 
  from 
  the 
  sandstone 
  highlands 
  bordering 
  the 
  

   Cuzco 
  basin 
  on 
  the 
  south, 
  — 
  valleys 
  from 
  which 
  terraces 
  and 
  

   slides 
  have 
  been 
  removed 
  and 
  whose 
  banks 
  offered 
  no 
  tempta- 
  

   tion 
  to 
  occupation, 
  valleys 
  whose 
  present 
  precipitous 
  gravel 
  

   walls 
  are 
  clearly 
  of 
  glacial 
  age, 
  — 
  no 
  traces 
  of 
  human 
  occupa- 
  

   tion 
  were 
  revealed 
  by 
  careful 
  search. 
  From 
  these 
  same 
  

   gravels, 
  however, 
  mastodon 
  bones 
  have 
  been 
  collected, 
  on 
  the 
  

   Huancaro 
  and 
  in 
  the 
  lower 
  Cuzco 
  valley. 
  The 
  fact 
  that 
  these 
  

   bones 
  from 
  the 
  Ayahuaycco 
  gravels 
  are 
  of 
  modern 
  types 
  (see 
  

   article 
  by 
  Eaton, 
  p. 
  5) 
  obviously 
  corroborates 
  this 
  view 
  of 
  

   depositional 
  history, 
  and 
  also 
  indicates 
  important 
  climatic 
  

   changes 
  since 
  the 
  Spanish 
  conquest. 
  

  

  It 
  will 
  be 
  noted 
  that 
  the 
  explanations 
  given 
  in 
  this 
  paper 
  

   are 
  chiefly 
  of 
  negative 
  value 
  so 
  far 
  as 
  archaeological 
  research 
  is 
  

   concerned. 
  That 
  man 
  existed 
  in 
  South 
  America 
  in 
  glacial 
  or 
  

   preglacial 
  times, 
  and 
  that 
  the 
  human 
  bones 
  discovered 
  in 
  the 
  

   Ayahuaycco 
  Quebrada 
  u 
  appear 
  to 
  be 
  from 
  20,000 
  to 
  40,000 
  

   years 
  old 
  " 
  as 
  tentatively 
  held 
  by 
  Bowman,* 
  is 
  not 
  definitely 
  

   disproven 
  by 
  the 
  field 
  studies 
  of 
  the 
  present 
  writer. 
  On 
  the 
  

   other 
  hand, 
  the 
  geologic 
  data 
  do 
  not 
  require 
  more 
  than 
  a 
  few 
  

   hundreds 
  of 
  years 
  as 
  the 
  age 
  of 
  the 
  human 
  remains 
  found 
  in 
  

   the 
  Cuzco 
  gravels. 
  

  

  *This 
  Journal, 
  vol. 
  xxxiii, 
  p. 
  321, 
  1912. 
  

  

  