## Radiometric Dating

*Absolute *__clocks__ based upon the loss of unstable elements in combination with the accumulation, within samples, of products of __nuclear fission__.

Also known simply as radiodating, radiometric dating is a type of absolute dating. Commonly used approaches in paleontology include __carbon dating__ (for more recent samples) and __potassium-argon__ dating (for older samples). Contrast relative dating.

Key to the process is a means by which the these clocks, which are based on __radioactive decay__, are started. This involves either the accumulation of a set ratio of isotopes that are then fixed at the point of organism death (carbon dating) or instead a purging of a sample of accumulated fission products (potassium-argon dating).

In radiometric dating either a sample of remains, or instead surrounding strata, is analyzed to determine ratios of isotopes or elements that are present. If it is the remains that are sampled (for carbon dating), then it can be assigned an absolute date. If it is surrounding layers, such as __volcanic ash__ (for potassium-argon dating), then the sample can be assigned a date that is relative to that of strata (such as *older* than an overlying ash layer or younger than a lower layer).

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