Dendrochronology absolute dating method

18-Jun-2019 22:40 by 5 Comments

Dendrochronology absolute dating method

Tree rings provided truly known-age material needed to check the accuracy of the carbon-14 dating method.

There have been many calibration curves published since Suess’s curve, but their proliferation brought more problems than solutions.

It is also worth noting that the half-life used in carbon dating calculations is 5568 years, the value worked out by chemist Willard Libby, and not the more accurate value of 5730 years, which is known as the Cambridge half-life.

Although it is less accurate, the Libby half-life was retained to avoid inconsistencies or errors when comparing carbon-14 test results that were produced before and after the Cambridge half-life was derived.

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.

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.

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.

Calibration of radiocarbon results is needed to account for changes in the atmospheric concentration of carbon-14 over time.

Libraries of tree rings of different calendar ages are now available to provide records extending back over the last 11,000 years.

The trees often used as references are the bristlecone pine (Pinus aristata) found in the USA and waterlogged Oak (Quercus sp.) in Ireland and Germany.

In later years, the use of accelerator mass spectrometers and the introduction of high-precision carbon dating have also generated calibration curves.