Crossdating
Definition
The matching of ring-width patterns between two or more samples to determine their relative or absolute temporal relationship. The master method of dendrochronology: a pattern of wide and narrow rings is unique enough that it can be matched against a reference chronology and assigned a calendar date.
- Field
- Dendrochronology
- Method
- Matching ring-width patterns between samples
- Output
- Relative or absolute calendar dating
- Requires
- A reference chronology to match against
Common questions
Why does matching ring widths give a reliable date rather than a guess?+
Trees in the same region tend to lay down similarly wide or narrow rings in the same years, driven by shared conditions like drought or a good growing season. That shared pattern is distinctive enough that a run of rings can be matched to its unique position in a long reference chronology built from many trees.
What happens if no reference chronology exists for the region or species involved?+
Without a reference chronology, crossdating can still establish the relative order and duration between samples, such as which piece of timber is older, but it cannot assign an absolute calendar date to the rings.
Related terms
- Annual Ring
- A single year's growth increment visible as a concentric band in a transverse wood section. In most temperate trees, each ring consists...
- Floating Chronology
- A ring-width sequence whose pattern is internally consistent but whose absolute calendar position is unknown because it cannot yet be crossdated to...
- Master Chronology
- A continuous, absolutely dated ring-width sequence built by overlapping many individual samples, living trees linked to old timbers and subfossil wood. Regional...
- Missing Ring
- A year in which growth was so suppressed, by extreme drought, frost, or injury, that no visible ring was deposited. Missing rings...
- Sapwood
- The outer living wood of a tree, typically lighter in colour than the dark heartwood. Species have characteristic sapwood ring counts (a...