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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  can 
  establish 
  the 
  way 
  in 
  which 
  different 
  regions 
  act 
  and 
  -react 
  at 
  the 
  

   same 
  time, 
  then 
  it 
  may 
  become 
  possible 
  to 
  determine 
  the 
  age 
  of 
  an 
  

   ancient 
  buried 
  tree 
  by 
  finding 
  the 
  combination 
  of 
  short 
  cycles 
  its 
  

   rings 
  display 
  and 
  then 
  determining 
  when 
  this 
  combination 
  or 
  its 
  

   regional 
  equivalent 
  existed 
  in 
  our 
  historic 
  measuring 
  tape, 
  the 
  great 
  

   sequoia. 
  

  

  VIII. 
  PREHISTORIC 
  RECORDS 
  IN 
  TREES. 
  

  

  A 
  new 
  method 
  of 
  investigating 
  the 
  relative 
  age 
  of 
  prehistoric 
  ruins 
  

   has 
  been 
  developed 
  in 
  connection 
  with 
  this 
  study 
  of 
  climate 
  by 
  

   the 
  growth 
  of 
  trees, 
  and 
  is 
  being 
  applied 
  to 
  the 
  remarkable 
  ruins 
  

   at 
  Aztec, 
  in 
  northwestern 
  New 
  Mexico, 
  with 
  its 
  450 
  rooms, 
  now 
  in 
  

   process 
  of 
  excavation 
  by 
  the 
  American 
  Museum 
  of 
  New 
  York 
  City. 
  

   The 
  ceilings 
  were 
  built 
  of 
  tree 
  trunks 
  placed 
  across 
  the 
  width 
  of 
  

   the 
  rooms. 
  Smaller 
  poles 
  were 
  laid 
  across 
  these 
  beams 
  and 
  covered 
  

   with 
  some 
  kind 
  of 
  brush 
  and 
  a 
  thick 
  layer 
  of 
  earth. 
  The 
  beams 
  

   used 
  in 
  this 
  ceiling 
  construction 
  are 
  almost 
  entirely 
  of 
  yellow 
  pine 
  

   or 
  spruce 
  and 
  for 
  the 
  most 
  part 
  are 
  in 
  good 
  condition. 
  Many 
  of 
  

   the 
  rooms 
  have 
  been 
  hermetically 
  sealed 
  for 
  centuries. 
  The 
  beams 
  

   which 
  have 
  been 
  buried 
  in 
  dust 
  or 
  adobe 
  or 
  in 
  sealed 
  rooms 
  are 
  

   well 
  preserved. 
  Only 
  those 
  which 
  have 
  been 
  exposed 
  to 
  the 
  air 
  

   are 
  decayed. 
  

  

  In 
  1915, 
  Dr. 
  Clark 
  Wissler 
  of 
  the 
  American 
  Museum 
  offered 
  

   sections 
  of 
  such 
  beams 
  for 
  special 
  study 
  of 
  the 
  rings, 
  knowing 
  the 
  

   writer's 
  work 
  upon 
  climatic 
  effects 
  in 
  the 
  rings 
  of 
  trees. 
  This 
  offer 
  

   was 
  gladly 
  accepted, 
  and 
  some 
  preliminary 
  sections 
  were 
  sent 
  at 
  

   once 
  from 
  the 
  Eio 
  Grande 
  region. 
  These 
  first 
  sections 
  showed 
  that 
  

   the 
  pines 
  and 
  spruces 
  were 
  far 
  better 
  than 
  cedars 
  for 
  determining 
  

   climatic 
  characteristics. 
  

  

  The 
  next 
  lot 
  of 
  sections 
  came 
  from 
  Aztec 
  and 
  was 
  cut 
  from 
  

   loose 
  beams 
  which 
  had 
  been 
  cleared 
  out 
  of 
  the 
  rubbish 
  heaps. 
  Six 
  

   of 
  these 
  sections 
  cross-identified 
  so 
  perfectly 
  that 
  it 
  was 
  evident 
  

   that 
  they 
  had 
  been 
  living 
  trees 
  at 
  the 
  same 
  time. 
  This 
  success 
  led 
  

   to 
  my 
  visit 
  to 
  Aztec 
  in 
  1919 
  and 
  a 
  close 
  examination 
  of 
  this 
  won- 
  

   derful 
  ruin. 
  It 
  was 
  at 
  once 
  apparent 
  that 
  an 
  instrument 
  was 
  nec- 
  

   essary 
  for 
  boring 
  into 
  the 
  beams 
  to 
  procure 
  a 
  complete 
  sample 
  of 
  

   the 
  rings 
  from 
  center 
  to 
  outside, 
  and 
  that 
  the 
  process 
  must 
  avoid 
  

   injuring 
  the 
  beams 
  in 
  any 
  way. 
  Such 
  an 
  instrument 
  was 
  de- 
  

   veloped 
  in 
  the 
  tubular 
  borer 
  as 
  already 
  described. 
  This 
  tool 
  was 
  

   sent 
  to 
  Mr. 
  Morris 
  and 
  during 
  1920 
  he 
  bored 
  into 
  all 
  the 
  beams 
  at 
  

   Aztec 
  then 
  available 
  and 
  sent 
  me 
  the 
  cores. 
  

  

  These 
  cores, 
  together 
  with 
  other 
  sections 
  of 
  beams 
  too 
  frail 
  for 
  

   boring, 
  finally 
  represented 
  37 
  different 
  beams 
  in 
  some 
  20 
  different 
  

   rooms 
  scattered 
  along 
  the 
  larger 
  north 
  part 
  of 
  the 
  ruin. 
  Prac- 
  

   tically 
  all 
  of 
  these 
  show 
  similar 
  rings 
  near 
  the 
  outside, 
  and 
  by 
  

  

  