Young earth radiometric dating

05 Jul

Using the known rate of change in radio-active elements (radiometric dating), some Earth rocks have been shown to be billions of years old, while the oldest solar system rocks are dated at 4.6 billion years.

Astronomers use the distance to galaxies and the speed of light to calculate that the light has been traveling for billions of years.

This method can even be used on dead trees that fell in a forest long ago.

For example, the last 200 rings in the dead tree might match up with 200 rings early in the life of the living tree, so the two trees together can count back many years.

Once the rock hardens, however, all the Argon-40 is trapped in the sample, giving us an accurate record of how much Potassium-40 has decayed since that time.

So, if we find a rock with equal parts Potassium-40 and Argon-40, we know that half the Potassium-40 has decayed into Argon-40, and that the rock hardened 1.3 billion years ago.

The half-life is the time that it takes for half the radioactive sample to change from one element into the other.

Some isotopes have short half-lives of minutes or years, but Potassium-40 has a half-life of 1.3 billion years.

Scientists have drilled ice cores deep into glaciers and found ice that is 123,000 years old in Greenland In your high school science classroom, you may have seen a large poster of the periodic table hanging on the wall.Radiometric dating requires that one understand the initial ratio of the two elements in a given sample by some means.In this case, Argon-40 is a gas that easily bubbles out and escapes when it is produced in molten rock.The annual ice layers in glaciers provide a similar method that goes back much further in history.Each year, snowfall varies throughout the seasons and an annual layer is formed.