Scientific methods are used to date the old age of swamp kauri wood found in northern New Zealand.
Technical background about Carbon Dating
Radiocarbon dating is the method by which archaeologists, geologists and other scientists date the past. There are two radiocarbon dating laboratories in New Zealand; the Waikato Radiocarbon Dating Laboratory at the University of Waikato in Hamilton and the Rafter Radiocarbon Laboratory at Geological & Nuclear Sciences in Wellington.
Space is filled with cosmic rays, which hit the upper layers of the Earth’s atmosphere. Atomic nuclei, hit by these rays, fragment and smaller particles (neutrons) are created. These neutrons fly about impacting other nuclei.
The impact of a neutron upon a nitrogen-14 (14N) atom results in the removal of a proton and the formation of a particle of carbon-14.
Carbon-14, or 14C, is an unstable, or radioactive atomic particle. On average, a particle of 14C will exist on Earth for 8033 years, before it decays, or changes back to 14N by losing an electron. This process of radioactive decay is the basis for the radiocarbon dating method.
The 14C atoms rapidly oxidize, and become carbon dioxide (CO2). This carbon dioxide becomes incorporated in plants through the process of photosynthesis, and into animals via the food chain.
Throughout their lives, trees like Kauri take up 14C from the atmosphere. Some of the 14C will decay during the life of the organism, but the decay will be offset by ongoing photosynthesis, so the 14C level in the wood of the tree will be maintained.
When a Kauri tree dies, it no longer takes up CO2 and cannot obtain any new 14C. The 14C atoms begin to disappear, or decay, back to 14N and the number of 14C atoms start to reduce.
The Process of Carbon Dating New Zealand Swamp Kauri
In the 1940s a team of scientists led by the late Willard Libby, of the University of Chicago, succeeded in discovering the ‘half life’ of ‘radiocarbon’ (14C). They found that after death, half of the 14C remaining in a given sample of carbon would disappear in 5568 years. In another 5568 years, another half of the remaining 14C would decay, and so on, until after about 10 half-lives no more 14C would remain.
In the laboratory, the wood from the tree is pretreated to remove any contaminating carbon.
The wood is converted into benzene (C6H6), which contains a high concentration of carbon atoms. First, the sample is combusted, or burnt. This produces CO2.
Then the CO2 is reacted with lithium and water to produce acetylene gas. This acetylene is then converted into benzene using a catalyst.
A scintillator is dissolved in the benzene. This reacts to the decay of 14C by releasing a flash of light. These light impulses are detected using a Liquid Scintillation Spectrometer. Finally, a radiocarbon age is calculated by comparing the measured 14C in the sample with standards of known age.
A radiocarbon date is published as an age + - error. The limit of the method varies between labs, but is generally around 60,000 years. Therefore, although many Kauri trees have been found in swamp and peat deposits radiocarbon dated to 40 – 60,000 years there are many which are older still and cannot be dated with radiocarbon.
Source: Drs. Tom Higham and Fiona Petchy, of the Radiocarbon Dating Laboratory at Waikato University in Hamilton.
Disclaimer: Ancient Kauri Kingdom uses the Waikato University to complete radiocarbon dating tests on our Ancient Kauri.
Radio carbon dating conducted around the world for Ancient Kauri Kingdom
Ancient Kauri Kingdom and our distributors have also had samples independently radiocarbon dated all over the world including Australia, Japan, USA, UK, Italy and Germany. All samples have returned radiocarbon dating results of more than 40,000 years.