Cross-dating patterns
Suitable species and environments produce seasonal rings whose widths respond to moisture, temperature and other conditions. Shared regional patterns permit comparison across trees; one isolated wide ring is insufficient.
Overlapping sequences from living and older wood extend chronologies backwards. Counting eighty rings alone does not identify which eighty calendar years they represent: reliable cross-dating supplies that placement.
References: [1]
The last ring and the archaeological event
Bark or the outermost growth can help establish the final growth year. If outer rings are missing, the last surviving ring cannot automatically be treated as the felling year.
Even a felling or death date need not equal construction: wood can be stored or reused. Component position and other evidence remain necessary to relate ring dates to building activity.
Preservation and environmental interpretation
Not every wood sample cross-dates successfully. Ring visibility, sequence length and appropriate regional reference series matter. At Tonto, many collected specimens yielded only a limited number of confirmed dates.
Environmental interpretation also depends on species and growing conditions. A well-watered riverside tree need not register variation like a rainfall-limited tree. Ring widths cannot automatically be read as a regional rainfall record.
References: [1]