That's all you really need to know to understand radiometric dating techniques. In the next part of this article, I'll examine several different radiometric dating techniques, and show how the axioms I cited above translate into useful age measurements. Common Methods of Radiometric Dating This section describes several common methods of radiometric dating. C14 is radioactive, with a half-life of 5730 years.

To start, let's look at one that almost everyone has heard of: radiocarbon dating, AKA "carbon-14 dating" or just "carbon dating." Method 1: Carbon-14 Dating The element carbon occurs naturally in three isotopes: C12, C13, and C14. C14 is also formed continuously from N14 (nitrogen-14) in the upper reaches of the atmosphere.

Some isotopes can break down in more than one way -- in these cases, each different breakdown type has its own half-life.

The decay rate and therefore the half-life are fixed characteristics of an isotope. That's the first axiom of radiometric dating techniques: the half-life of a given isotope is a constant.

So the dates derived from C14 decay had to be revised.

One reference on radiometric dating lists an entire array of corrective factors for the change in atmospheric C14 over time.

The new atom doesn't form the same kinds of chemical bonds that the old one did. It may not even be able to hold the parent atom's place in the compound it finds itself in, which results in an immediate breaking of the chemical bonds that hold the atom to the others in the mineral. (The exact details of this are rather complicated, so I won't go into them here.) When the number of electrons change, the shell structure changes too.

So when an atom decays and changes into an atom of a different element, its shell structure changes and it behaves in a different way chemically. That's the sum total of the chemical and physical basis of radiometric dating.

When I first became interested in the creation-evolution debate, in late 1994, I looked around for sources that clearly and simply explained what radiometric dating is and why young-Earth creationists are driven to discredit it.When we know how much has decayed, we know how old the sample is.Many archaeological sites have been dated by applying radiocarbon dating to samples of bone, wood, or cloth found there. One is that the thing being dated is organic in origin.The second assumption is that the organism in question got its carbon from the atmosphere.A third is that the thing has remained closed to C14 since the organism from which it was created died.