Wiens has a Ph D in Physics, with a minor in Geology.His Ph D thesis was on isotope ratios in meteorites, including surface exposure dating.

Some of the atoms eventually change from one element to another by a process called radioactive decay.

If there are a lot of atoms of the original element, called the parent element, the atoms decay to another element, called the daughter element, at a predictable rate.

Many people have been led to be skeptical of dating without knowing much about it. In spite of this, differences still occur within the church.

For example, most people don't realize that carbon dating is only rarely used on rocks. A disagreement over the age of the Earth is relatively minor in the whole scope of Christianity; it is more important to agree on the Rock of Ages than on the age of rocks.

Radiometric dating--the process of determining the age of rocks from the decay of their radioactive elements--has been in widespread use for over half a century.

There are over forty such techniques, each using a different radioactive element or a different way of measuring them.

This paper describes in relatively simple terms how a number of the dating techniques work, how accurately the half-lives of the radioactive elements and the rock dates themselves are known, and how dates are checked with one another.

In the process the paper refutes a number of misconceptions prevalent among Christians today.

Radiometric dating techniques indicate that the Earth is thousands of times older than that--approximately four and a half billion years old.