The Tree-Ring Date Spreadsheet


We have compiled an Excel spreadsheet of tree-ring dates from several of the great houses in Chaco Canyon and from Aztec using a variety of sources and the help of several individuals:

  • The 1970s publications of the Laboratory of Tree-Ring Research at the University of Arizona for New Mexico areas A-G-H and B (Bannister, Robinson, and Warren 1970; Robinson, Harrill, and Warren 1974).
  • Dates obtained by Tom Windes and Dabney Ford of the National Park Service (Windes and Ford 1992, 1996; Windes and McKenna 2001), with the help of a large group of volunteers, during the recent Chaco Wood Project.  Windes entered information for each sample into dBase III files.  Hannah Fretwell of the Department of Anthropology at the University of New Mexico, working with Windes, Wendy Bustard, and Chip Wills, converted the files into Access files for each individual site.  We then used Access to generate Excel files that were imported into our spreadsheet.
  • Electronic database files for some sites that were provided in the fall of 2003 by Jeff Dean that include dates obtained since the Tree-Ring Laboratory’s 1970s publications.  These original files were created in FirstChoice, an early database program.  We purchased a program to convert them to the Excel format. 
  • Dates on paper sent from Jeff Dean at the Tree ring lab
  • Dates for Chetro Ketl provided by Dean and Warren (1983) in Lekson’s (1983) Chetro Ketl report.

The source(s) of the data are provided in the spreadsheet.  The “Remarks” column also includes some notes on discrepancies among sources and questions of interpretation.  In many cases there was overlap between these five sources.  If, in such cases, the reported dates differed somewhat, priority was given to the dates provided directly by the Laboratory of Tree-Ring Research in sources 1) and 3) above.

The standard codes employed by the Laboratory of Tree-Ring Research are listed in separate columns from the inside date (“Inside Code”) and outside date (“Outside code”). Species information is provided when available.  Species abbreviations are as follows:

  1. ALDR-ALDER
  2. DF- Douglas Fir
  3. JUN-- juniper
  4. N/A - Used by CDI to indicate that species identification was not provided by a particular publication, in this case Tree Ring Dates from New Mexico B.
  5. NONCON - Unidentified nonconiferous species
  6. PNN - pinyon pine
  7. POP - poplar
  8. PP - pondersosa pine
  9. SAGE - sage
  10. SF - spruce (Picea) or fir (Abies)
  11. SPRU - spruce
  12. UNK - Uknown
  13. TENT - Tentative and unable to be cross-dated because of too few rings.

Before downloading the spreadsheet, we recommend you read the following disclaimer. Please note: there is a key for the spreadsheet explaining the coding system. This document must be downloaded separately.

Download Spreadsheet | Download Key | References