(den-droh-cruh-NOL-uh-gee) means “the study of tree time.” Usually called tree-ring dating, dendrochronology is a science based on the fact that every growth season a tree adds a new layer of wood to its trunk.
Over time, these yearly growth layers form a series of light and dark concentric circles, or tree rings, that are visible on cross sections of felled trees.
Generally, it is not possible to construct a complete sequence of tree rings back through the historical periods using only living trees.
Chronologies derived from living trees must be extended.
It should be noted that a BP notation is also used in other dating techniques but is defined differently, as in the case of thermoluminescence dating wherein BP is defined as AD 1980.Example: analyzing the effects of air pollution on tree growth by studying changes in ring widths over time.The science that uses tree rings to date earth surface processes that created, altered, or shaped the landscape.This results in the cambium cells becoming smaller and thicker-walled.By winter, when the sap finally stops flowing, a smooth dark ring marks the end of the tree’s annual growth.