Chronometric dating method based on the principle
in dry climates
tend to accumulate one growth
ring per year, so the number of rings indicates the age
of a tree
in years. The width of a ring varies according to climate
: as wet years result in broader rings. A specific
tree-ring pattern can be compared with a sequential master chart of such rings for a given region, which typically covers the past 10 000 years or so. First applied in 1901.