Fluorine absorption dating is a method used to determine the amount of time an object has been underground. Fluorine absorption dating can be carried out based on the fact that

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

contains fluoride ions. Items such as

bone A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...

that are in the soil will absorb fluoride from the groundwater over time. From the amount of absorbed fluoride in the item, the time that the item has been in the soil can be estimated. Many instances of this dating method compare the amount of fluorine and uranium in the bones to

nitrogen dating Nitrogen dating is a form of relative dating which relies on the reliable breakdown and release of amino acids from bone samples to estimate the age of the object. For human bones, the assumption of about 5% nitrogen in the bone, mostly in the fo ...

to create more accurate estimation of date. Older bones have more fluorine and uranium and less nitrogen. But because

decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...

happens at different speeds in different places, it's not possible to compare bones from different sites. As not all objects absorb fluorine at the same rate, this also undermines the accuracy of such a dating technique. Although this can be compensated for by accommodating for the rate of absorption in calculations, such an accommodation tends to have a rather large

margin of error The margin of error is a statistic expressing the amount of random sampling error in the results of a survey. The larger the margin of error, the less confidence one should have that a poll result would reflect the result of a census of the ent ...

. In 1953 this test was used by

Kenneth Oakley Kenneth Page Oakley (7 April 1911 – 2 November 1981) was an English Physical anthropology, physical anthropologist, palaeontologist and geologist. Oakley, known for his work in the Fluorine absorption dating of fossils by fluorine content, ...

to easily identify that the '

Piltdown Man The Piltdown Man was a paleoanthropological fraud in which bone fragments were presented as the fossilised remains of a previously unknown early human. Although there were doubts about its authenticity virtually from the beginning, the remains ...

' was forged, almost 50 years after it was originally 'unearthed'.

References

* Göksu, H. Y., M. Oberhofer and D. Regulla, editors, ''Fluorine dating'' in ''Scientific Dating Methods,'' Springer, 1991, pp 251 – 270 {{DEFAULTSORT:Fluorine Absorption Dating Dating methodologies in archaeology