What scientific method uses tree rings to date wood and past events?

The scientific method that uses tree rings to date wood and past events is dendrochronology.

Dendrochronologists compare patterns of narrow and wide growth rings among trees and wooden objects. Because weather and other environmental conditions affect growth across a region, matching these patterns can connect a timber sample to a precisely dated chronology. A complete outer edge can sometimes reveal the year a tree was felled.

The method is especially valuable in archaeology, where it can date beams, buildings, tools, coffins, and wooden artworks. It also supports dendroclimatology: ring widths and other ring characteristics preserve evidence about past droughts, cold periods, and growing conditions.

Dendrochronology is not identical to simply counting rings. Counting can estimate age, but cross-dating patterns against reference sequences provides calendar years. It also differs from radiocarbon dating, which usually produces a calibrated age range rather than a direct exact ring year. The name combines Greek roots for tree, time, and study.