Forms of radiometric dating
Its crust is continually being created, modified, and destroyed.
The principal evidence for the antiquity of Earth and its cosmic surroundings is: Spontaneous breakdown or decay of atomic nuclei, termed radioactive decay, is the basis for all radiometric dating methods.
All rocks and minerals contain long-lived radioactive elements that were incorporated into Earth when the Solar System formed.
These radioactive elements constitute independent clocks that allow geologists to determine the age of the rocks in which they occur.
If an igneous or other rock is metamorphosed, its radiometric clock is reset, and potassium-argon measurements can be used to tell the number of years that has passed since metamorphism.
Carbon-14 is a method used for young (less than 50,000 year old) sedimentary rocks.
Radioactivity was discovered in 1896 by French physicist Henri Becquerel.