Accurate dates also allow us to create sequences of evolutionary change and work out when species appeared or became extinct. These are: Where possible, several different methods are used and each method is repeated to confirm the results obtained and improve accuracy.Different methods have their own limitations, especially with regard to the age range they can measure and the substances they can date.When volcanic rocks and minerals are formed, they do not contain fission tracks.
After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay.
Carbon-14 has a half-life of 5,730 ± 40 years, meaning that every 5,700 years or so the object loses half its carbon-14.
During this process the pieces of the atom move apart at high speed, causing damage to the rock or mineral.
This damage is in the form of tiny marks called fission tracks.
By examining the object's relation to layers of deposits in the area, and by comparing the object to others found at the site, archaeologists can estimate when the object arrived at the site.
Though still heavily used, relative dating is now augmented by several modern dating techniques.
Anderton and co; Dr Ian West, A Geologic Time Scale 2004, by F. Discovering Fossils provides a free resource to inform you about this fascinating subject and does not accept any liability for decisions made using this information.
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Toghill; British Regional Geology, The Midland Valley; en.wikipedia.org; A Dynamic Stratigraphy of the British Isles, R. Picture credits: Mackenzie delta by Lois Brown at dragonfly by 'pjayres' at jungle palm by 'janeandpoppy' at Arthropleura from
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Green plants absorb the carbon dioxide, so the population of carbon-14 molecules is continually replenished until the plant dies.