What type of rock is used for radiometric dating

To determine the ages of these specimens, scientists need an isotope with a very long half-life.

what type of rock is used for radiometric dating-13

Scientists have also made improvements to the standard radiometric measurements.

For example, by using a laser, researchers can measure parent and daughter atoms in extremely small amounts of matter, making it possible to determine the age of very small samples [source: New Scientist].

Radiometric dating isn't the only method of determining the age of rocks.

Other techniques include analyzing amino acids and measuring changes in an object's magnetic field.

This information has also helped determine the age of the Earth itself.

While the oldest known rocks on Earth are about 3.5 billion years old, researchers have found zircon crystals that are 4.3 billion years old [source: USGS].

So to determine the age of sedimentary rock layers, researchers first have to find neighboring layers of Earth that include igneous rock, such as volcanic ash.

These layers are like bookends -- they give a beginning and an end to the period of time when the sedimentary rock formed.

As radioactive Parent atoms decay to stable daughter atoms (as uranium decays to lead) each disintegration results in one more atom of the daughter than was initially present and one less atom of the parent.

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