Gives scientist an exact age of a rock fossil.

Relative Dating, in which fossils and layers of rock are placed in order from older to younger

The process that scientist use to find the exact age of a fossil or rock. Scientists use atoms to determine the age of certain objects or even rocks. They measure the radioactive isotopes in the material. Over time, radioactive isotopes give off energy. This results in a complete change in the atom. The amount of time it takes for half of the radioactive isotopes in the material to go through this complete change is called the half life. Scientists use what they know about the half life of certain materials to measure the age of the material.