Carbon 14 dating chart
Calibration is not only done before an analysis but also on analytical results as in the case of radiocarbon dating—an analytical method that identifies the age of a material that once formed part of the biosphere by determining its carbon-14 content and tracing its age by its radioactive decay.Carbon-14 is a naturally occurring isotope of the element carbon.
Post-modern data are very useful in some cases in illustrating a calendar age of very young materials (Hua, et. Atmospheric Radiocarbon for the period 1950-2010, Radiocarbon, 55(4), 2013).The first calibration curve for radiocarbon dating was based on a continuous tree-ring sequence stretching back to 8,000 years.This tree-ring sequence, established by Wesley Ferguson in the 1960s, aided Hans Suess to publish the first useful calibration curve.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.In later years, the use of accelerator mass spectrometers and the introduction of high-precision carbon dating have also generated calibration curves.
A high-precision radiocarbon calibration curve published by a laboratory in Belfast, Northern Ireland, used dendrochronology data based on the Irish oak.
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.
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.
And indeed, results of calibration are often given as an age range rather than an absolute value.