Radiometric dating calibration

When a living organism dies, it no longer takes in carbon, and the C-14 it contains at the time of death continues to decay and revert to normal nitrogen.The longer a once-living thing has been dead – whether it is wood or bone – the less C-14 it contains.Carbon-14 decays relatively quickly, and at about 50,000 years after the death of the organism no C-14 atoms will be left in the remains. As in the case of the other radiometric methods, the technique consists of measuring the ratio of C-14 to C-12 in the specimen and calculating the age based on the known rate of decay.

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In fact, wood from dated coffins was used in the early work that established this method.

However, the method is really only reliable within the limits of calibration, and even then there are some problems.

It is well known, for example, that materials older than about 3,000 years begin to yield much older ages.

Conversely, those who believe in the old ages have always complained that the C-14 method gives ages that are too young.

The carbon-14 method is slightly different from other dating methods. Carbon-14 is the unstable form produced by cosmic ray bombardment of nitrogen in the earth's upper atmosphere.

The C-14 combines with oxygen to form carbon dioxide, which then takes its place in the great carbon cycle.That is, the carbon dioxide becomes the food for plants and trees, and these in turn become food for animals and humans.The net result is that every living thing contains normal carbon (C-12) and some C-14."Fudge factors" have to be employed to bring the reported ages within the limits of the expected dates! One of the principle problems of the method lies in the assumption that C-14 has been produced in the upper atmosphere for millions of years and that it long ago reached a steady state.In other words, the amount of C-14 now being generated is exactly equal to that being lost by decay.However, measurements show that C-14 is still rapidly building up in the atmosphere.

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