Issues regarding the tree-ring samples in the Chaco Research Archive database

The list of tree-ring samples in the CRA database is the total sample available to us from the Laboratory of Tree-Ring Research, the Chaco Culture National Park Museum Collection, and published sources.  As with all dates, there are important issues to be considered in their interpretation and we refer the user to Jeff Dean’s seminal publication “Independent Dating in Archaeological Analysis,” for a succinct discussion of issues with tree-ring dates.

In Chaco Canyon and in other locations such as Aztec Ruin, reuse of wood is a particularly important concern because of the long history of stabilization work at many greathouses. For example, two catastrophic events–the fall of Threatening Rock into Pueblo Bonito in 1941 and the flooding of Chetro Ketl in 1947–generated hundreds of beams that were salvaged and later used during stabilization activities in great houses throughout Chaco Canyon and the park-owned outliers.  Additional prehistoric samples were collected during stabilization activities between 1940 and 1970 and stockpiled for later reuse.  Thus, dates of beams taken from one site ultimately may have been mixed with samples derived from other great houses.  Reused prehistoric wood is also a problem at Aztec Ruins, where many pieces were reused during stabilization of the Aztec West Ruin. A few pieces at Aztec are also documented as having origins in Mesa Verde National Park, and a few pieces from Aztec were used during stabilization at Cliff Palace.

Users should be aware that additional provenience information is available for some samples and not for others.  Also, in a few rare cases there are two data records listed for a single tree ring sample in cases where a sample was analyzed twice with divergent dates.

For more information on NPS stabilization projects, please see the Architectural Stabilization section of this website.

Work on the wood database continues as part of an overall NPS publication on the Chaco and Aztec structural wood.  For specific questions about recent dates collected during the Chaco Wood Project, contact Tom Windes at windes[at]unm.edu.

Dean, J.S. 1978. “Independent Dating in Archaeological Analysis.”  In: M.B. Schiffer, ed., Advances in Archaeological Method and Theory, vol. 1. Academic Press, New York: 223-255.