dendrochronology

/ˌdɛndrəkrəˈnɑləʤi/

Dendrochronology is the science of calculating how old a tree is by studying its growth rings. When you count fifty-two rings in the trunk of a felled tree and determine it's about 50 years old, that's basic dendrochronology.

Dendrochronology derives from the Greek roots dendron, meaning "tree"; khronos, meaning "time"; and -logia, meaning "the study of." Botanists who practice dendrochronology are experts in dating rings in the cross section of a tree trunk — determining the precise years each ring was formed. They can also learn details about the climate in specific years from examining these growth rings, which show evidence of cold snaps, droughts, and unusually warm temperatures.

Definitions of dendrochronology

1. noun

   the study of ancient trees to date environmental changes and past events, especially by measuring the rings of tree trunks