The context of the sample - whether from archaeological sites, a historic building, or a work of art - gives us a range of possible dates for the individual rings and the patterns contained in the rings.
Dendrochronology in general includes establishing calendar dates for samples and chronologies that include forest trees and historic sequences that securely crossdate; and establishing absolute dates for floating chronologies by securely crossdating the unknown sequences with other chronologies that are absolutely dated, or, if necessary, by radiocarbon wiggle-matching samples contained in the chronology.
In this way, the history of trees and their environment is reflected in their wood structure.
These records include evidence for both cataclysmic events and patterns of climate change over time, both at local and regional levels.
We are examining the structure of organic material created within a geographic region in the terrestrial ecosystem over time, a feature that is independent of most other records.
Interpreting the record of the tree-rings is the major focus of our lab.
Cross-dating is used with raw measurements or detrended data sets to establish the sequences' placement in time.
The principle of cross-dating is straightforward: trees of the same species growing in the same time in the same geographical region have similar tree-ring patterns.
Samples are collected by coring live trees, extant structural beams, boards, and rafters, and by taking cross-sections whenever possible.