Tree-Ring Databases

Laboratory of Tree-Ring Research

Database of Chaco Canyon Great House specimens

Researchers from the laboratory of Tree-Ring Research at the University of Arizona have recently (2015) compiled a database of tree-ring specimens from Chaco great house structures. The database was created independently from previous compilations, and thus it includes many already reported dates but adds substantially to those. It also includes specimens that could not be precisely dated by dendrochronology.

The database was compiled from the paper specimen notecards located on file at the Laboratory of Tree-Ring Research, and includes all available data on the cards. These data identify the specimens (e.g., a, b, c) associated with an individual sample (e.g., JPB-100), its inner and outer dates, the structure from where it was excavated, the unit within that structure, the year of sampling, the excavator, the LTRR lab interpreter, and the box in which the specimen is archived. Digitization of the specimen cards was done by LTRR curatorial specialist Greer Dove Flax, under the supervision of LTRR Curator Pearce Paul Creasman. These cards were scanned in the process, and will be made available online ( by the end of 2015.

This effort was carried out with funding from the Western National Parks Association, Grant 13-02 to Christopher Guiterman, Thomas Swetnam, Jeffrey Dean, and Pearce Paul Creasman, all of the laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ.

The CRA is in the process of reconciling the 2015 LTRR database with the tree-ring database that currently exists within the CRA relational database structure.

The 2015 LTRR database is available for download here:

Data citation:

Guiterman, C.H., T.W. Swetnam, and J.S. Dean

  • (in revision). An 11th Century Shift in Timber Procurement Areas for the Great Houses of Chaco Canyon. Proceedings of the National Academy of Sciences of the United States of America.

CRA Tree-Ring Database

The Chaco Research Archive had previously compiled an Excel spreadsheet of tree-ring dates from several of the great houses in Chaco Canyon and from Aztec Ruins 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.

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.

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 the Chaco Research Archive 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.

Tree Ring References

Bannister, Bryant, William J. Robinson, and Richard L. Warren

  • 1970 Tree-Ring Dates from New Mexico A, G-H, Shiprock-Zuni-Mt. Taylor Area. Laboratory of Tree-Ring Research, University of Arizona, Tucson

Dean, Jeffrey S., and Richard L. Warren

  • 1983 Dendrochronology. Chapter V in The Architecture and Dendrochronology of Chetro Ketl, Chaco Canyon, New Mexico, edited by Stephen H. Lekson, pp. 105-240. Reports of the Chaco Center No. 6. Division of Cultural Research, National Park Service, Albuquerque.

Lekson, Stephen H.

  • 1983c (editor) The Architecture and Dendrochronology of Chetro Ketl, Chaco Canyon, New Mexico. Reports of the Chaco Center No. 6. Division of Cultural Research, National Park Service, Albuquerque.

Robinson, William J., Bruce G. Harrill, and Richard L. Warren

  • 1974 Tree-ring Dates from New Mexico B: Chaco-Gobernador Area. The Laboratory of Tree-Ring Research, University of Arizona, Tucson.

Windes, Thomas C., and Dabney Ford

  • 1992 The Nature of the Early Bonito Phase. In Anasazi Regional Organization and the Chaco System, edited by David E. Doyel, pp. 75-85. Anthropological Papers No. 5. Maxwell Museum of Anthropology, University of New Mexico, Albuquerque.
  • 1996 The Chaco Wood Project: The Chronometric Reappraisal of Pueblo Bonito. American Antiquity 61 (2):295-310.

Windes, Thomas C., and Peter J. McKenna

  • 2001 Going Against the Grain. Wood Production in Chacoan Society. American Antiquity 66 (1):119-140.