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Dendrochronology is the scientific method of dating the growth rings of a tree to the exact years they were formed. The word is derived from Ancient Greek dendron (δένδρον), meaning "tree", khronos (χρόνος), "time", and -logia (-λογία), "the study of". The method is useful for determining the precise period over which the trees that the timbers were derived from were growing and when these trees were felled. These outermost rings may be lost during conversion of the tree into the timber element, or object, and in such instances a felling date estimate can be provided. The time elapsed between felling the tree and using the timber for construction is generally insignificant with usage commonly occurring within a year or two at most of felling.

Dendrochronology is used on wood found on archaeological sites and in historic buildings or in works of art, such as old panel paintings, or other portable artefacts, such as furniture. Uncertainty of the precise date of felling may arise from the absence of the rings nearest the outside of the tree, immediately under the bark. This makes it difficult to determine the time elapsed between felling the tree and using its wood for construction. A new method, based on measuring variations in oxygen isotopes in each ring, can yield accurate results on samples not suitable for the traditional technique.

The pattern of rings from the sample is matched against the known long-term pattern of rings from the same species of tree (in our case usually oak) in a similar geographical location (in our case central England), as illustrated in the diagram below. The position of highest correlation score gives the most probable date of the sample. More information can be found in the Historic England Guidelines on producing and interpreting dendrochronological dates.