The most widely used and accepted form of absolute dating is radioactive decay dating. Radioactive decay refers to the process in which a radioactive form of an element is converted into a nonradioactive product at a regular rate.

The nucleus of every radioactive element (such as radium and uranium) spontaneously disintegrates over time, transforming itself into the nucleus of an atom of a different element.

carbon 14 used carbon dating-74

The successive layers of rock represent successive intervals of time.

Since certain species of animals existed on Earth at specific times in history, the fossils or remains of such animals embedded within those successive layers of rock also help scientists determine the age of the layers.

In addition to the radiocarbon dating technique, scientists have developed other dating methods based on the transformation of one element into another.

These include the uranium-thorium method, the potassium-argon method, and the rubidium-strontium method. Thermoluminescence (pronounced ther-moeloo-mi-NES-ence) dating is very useful for determining the age of pottery.

Carbon-14, a radioactive form of the element carbon, is created in the atmosphere by cosmic rays (invisible, high-energy particles that constantly bombard Earth from all directions in space).

When carbon-14 falls to Earth, it is absorbed by plants.

Half-life: Measurement of the time it takes for one-half of a radioactive substance to decay.

Radioactive decay: The predictable manner in which a population of atoms of a radioactive element spontaneously disintegrate over time.

Cosmic rays: Invisible, high-energy particles that constantly bombard Earth from all directions in space.