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It uses the fact that natural carbon contains a known ratio of ordinary carbon and the radioactive isotope carbon-14, and that this mix is reflected in carbon taken up by living organic materials such as wood, shells and bones.
When organisms die, the carbon-14 begins to decay at a known rate.
They thought that sites which had the same kinds of pots and tools would be the same age.
The relative dating method worked very well, but only in sites which were had a connection to the relative scale. When radiocarbon dating was developed, it revolutionised archaeology, because it enabled them to more confidently date the past, and to build a more accurate picture of the human past.
In Nyerup's time, archaeologists could date the past only by using recorded histories, which in Europe were based mainly on the Egyptian calendar.
They used pottery and other materials in sites to date 'relatively'.
The method also assumes a 'zeroing' event in the life of the material, when it was either last heated or exposed to sunlight.
Radiocarbon analysis can only be used on organic materials, and is often used to date charcoal associated with campfires and archaeological deposits.
Dates above and below a location provide minimum and maximum age determinations according to the law of superimposition.
Thermoluminescence is a similar technique to optical dating, but uses heat instead of light to stimulate the minerals.
The measurement is based on an isotope of potassium that radioactively decays at a known rate into argon.
K-Ar dating has been used to date lava flows above and below archaeological deposits that contain important hominid fossils in Africa's Olduvai Gorge.
The person who wrote these words lived in the 1800s, many years before archaeologists could accurately date materials from archaeological sites using scientific methods.