They can determine the exact calendar year each tree ring was formed.Dendrochronological findings played an important role in the early days of radiocarbon dating.Radiocarbon measurements are based on the assumption that atmospheric carbon-14 concentration has remained constant as it was in 1950 and that the half-life of carbon-14 is 5568 years.
The tree rings were dated through dendrochronology.At present, tree rings are still used to calibrate radiocarbon determinations.Results of carbon-14 dating are reported in radiocarbon years, and calibration is needed to convert radiocarbon years into calendar years.Uncalibrated radiocarbon measurements are usually reported in years BP where 0 (zero) BP is defined as AD 1950.Tree rings provided truly known-age material needed to check the accuracy of the carbon-14 dating method.
During the late 1950s, several scientists (notably the Dutchman Hessel de Vries) were able to confirm the discrepancy between radiocarbon ages and calendar ages through results gathered from carbon dating rings of trees.
The science of dendrochronology is based on the phenomenon that trees usually grow by the addition of rings, hence the name tree-ring dating.
Dendrochronologists date events and variations in environments in the past by analyzing and comparing growth ring patterns of trees and aged wood.
These changes were brought about by several factors including, but not limited to, fluctuations in the earth’s geomagnetic moment, fossil fuel burning, and nuclear testing.
The most popular and often used method for calibration is by dendrochronology.
The first calibration curve for radiocarbon dating was based on a continuous tree-ring sequence stretching back to 8,000 years.