Geological and Archeological Applications

Carbon Dating and Determining Age

Scientists once believed the Earth to be less than 40 million years old. While that's a very long time, today's scientists now believe the Earth is around 460 million years old! Expert scientists, known as geologists, changed their thinking about Earth's age after they learned how to calculate the radioactive decay of the natural rock, uranium.

Other scientists, known as archeologists, can determine the age of plant and animal fossils-such as dinosaur bones-through a process called “carbon dating.” Because living things take in carbon from the atmosphere, they have a certain amount of carbon-14 in their tissues. Once they die, that amount changes as a result of radioactive decay. By comparing the amount of carbon-14 in the dead material to how much would be in a living plant or animal, archeologists can determine when the plants or animals lived.