Carbon 14 dating dendrochronology
It's development revolutionized archaeology by providing a means of dating deposits independent of artifacts and local stratigraphic sequences.
Animals eating those plants in turn absorb Carbon-14 as well as the stable isotopes.
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.
The wood in these rings once laid down remains unchanged during the life of the tree.
This is very useful as a record of the radiocarbon concentration in the past.